├── Design-Patterns.zip ├── PULL_REQUEST_TEMPLATE.md ├── source ├── footer.swift ├── structural │ ├── _title.swift │ ├── Proxy.swift │ ├── facade.swift │ ├── decorator.swift │ ├── bridge.swift │ ├── composite.swift │ ├── adapter.swift │ └── flyweight.swift ├── behavioral │ ├── _title.swift │ ├── Template-Method.swift │ ├── iterator.swift │ ├── strategy.swift │ ├── memento.swift │ ├── state.swift │ ├── interpreter.swift │ ├── command.swift │ ├── Chain-Of-Responsibility.swift │ ├── visitor.swift │ ├── observer.swift │ └── mediator.swift ├── creational │ ├── singleton.swift │ ├── _title.swift │ ├── prototype.swift │ ├── factory.swift │ ├── builder.swift │ └── Abstract-Factory.swift └── header.swift ├── GENERATE.md ├── Behavioral.playground ├── playground.xcworkspace │ └── contents.xcworkspacedata ├── Pages │ ├── Interpreter.xcplaygroundpage │ │ ├── timeline.xctimeline │ │ └── Contents.swift │ ├── Template-method.xcplaygroundpage │ │ └── Contents.swift │ ├── Iterator.xcplaygroundpage │ │ └── Contents.swift │ ├── Strategy.xcplaygroundpage │ │ └── Contents.swift │ ├── Memento.xcplaygroundpage │ │ └── Contents.swift │ ├── State.xcplaygroundpage │ │ └── Contents.swift │ ├── Chain-Of-Responsibility.xcplaygroundpage │ │ └── Contents.swift │ ├── Command.xcplaygroundpage │ │ └── Contents.swift │ ├── Observer.xcplaygroundpage │ │ └── Contents.swift │ ├── Visitor.xcplaygroundpage │ │ └── Contents.swift │ └── Mediator.xcplaygroundpage │ │ └── Contents.swift └── contents.xcplayground ├── Creational.playground ├── playground.xcworkspace │ └── contents.xcworkspacedata ├── contents.xcplayground └── Pages │ ├── Singleton.xcplaygroundpage │ └── Contents.swift │ ├── Prototype.xcplaygroundpage │ └── Contents.swift │ ├── Factory.xcplaygroundpage │ └── Contents.swift │ ├── Builder.xcplaygroundpage │ └── Contents.swift │ └── Abstract-Factory.xcplaygroundpage │ └── Contents.swift ├── Structural.playground ├── playground.xcworkspace │ └── contents.xcworkspacedata ├── contents.xcplayground └── Pages │ ├── Proxy.xcplaygroundpage │ └── Contents.swift │ ├── Facade.xcplaygroundpage │ └── Contents.swift │ ├── Decorator.xcplaygroundpage │ └── Contents.swift │ ├── Bridge.xcplaygroundpage │ └── Contents.swift │ ├── Composite.xcplaygroundpage │ └── Contents.swift │ ├── Adapter.xcplaygroundpage │ └── Contents.swift │ └── Flyweight.xcplaygroundpage │ └── Contents.swift ├── Design-Patterns.playground ├── playground.xcworkspace │ ├── contents.xcworkspacedata │ └── xcshareddata │ │ └── Design-Patterns.xccheckout ├── contents.xcplayground └── Pages │ ├── Creational.xcplaygroundpage │ └── Contents.swift │ ├── Structural.xcplaygroundpage │ └── Contents.swift │ └── Behavioral.xcplaygroundpage │ └── Contents.swift ├── .gitignore ├── generate-playground.sh ├── LICENSE └── README.md /Design-Patterns.zip: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/zsergey/Design-Patterns-In-Swift/HEAD/Design-Patterns.zip -------------------------------------------------------------------------------- /PULL_REQUEST_TEMPLATE.md: -------------------------------------------------------------------------------- 1 | 2 | 3 | - [ ] Do not change the `.playground` nor `README.md` manually. 4 | - [ ] Go to `/source` and edit .swift files. 5 | - [ ] Run: `generate-playground.sh` -------------------------------------------------------------------------------- /source/footer.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 3 | Info 4 | ==== 5 | 6 | 📖 Descriptions from: [Gang of Four Design Patterns Reference Sheet](http://www.blackwasp.co.uk/GangOfFour.aspx) 7 | 8 | */ 9 | -------------------------------------------------------------------------------- /GENERATE.md: -------------------------------------------------------------------------------- 1 | How to generate playground and zip 2 | ================================== 3 | 4 | In Terminal type: 5 | 6 | every time: 7 | 8 | ```bash 9 | ./generate-playground.sh 10 | ``` 11 | 12 | 👍 -------------------------------------------------------------------------------- /Behavioral.playground/playground.xcworkspace/contents.xcworkspacedata: -------------------------------------------------------------------------------- 1 | 2 | 4 | 6 | 7 | 8 | -------------------------------------------------------------------------------- /Creational.playground/playground.xcworkspace/contents.xcworkspacedata: -------------------------------------------------------------------------------- 1 | 2 | 4 | 6 | 7 | 8 | -------------------------------------------------------------------------------- /Structural.playground/playground.xcworkspace/contents.xcworkspacedata: -------------------------------------------------------------------------------- 1 | 2 | 4 | 6 | 7 | 8 | -------------------------------------------------------------------------------- /Design-Patterns.playground/playground.xcworkspace/contents.xcworkspacedata: -------------------------------------------------------------------------------- 1 | 2 | 4 | 6 | 7 | 8 | -------------------------------------------------------------------------------- /Design-Patterns.playground/contents.xcplayground: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # CocoaPods 2 | # 3 | # We recommend against adding the Pods directory to your .gitignore. However 4 | # you should judge for yourself, the pros and cons are mentioned at: 5 | # http://guides.cocoapods.org/using/using-cocoapods.html#should-i-ignore-the-pods-directory-in-source-control? 6 | # 7 | # Pods/ 8 | 9 | .DS_Store 10 | UserInterfaceState.xcuserstate 11 | -------------------------------------------------------------------------------- /source/structural/_title.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | -------------------------------------------------------------------------------- /Creational.playground/contents.xcplayground: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | -------------------------------------------------------------------------------- /source/behavioral/_title.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | -------------------------------------------------------------------------------- /source/creational/singleton.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 💍 Singleton 3 | ------------ 4 | 5 | The singleton pattern ensures that only one object of a particular class is ever created. 6 | All further references to objects of the singleton class refer to the same underlying instance. 7 | There are very few applications, do not overuse this pattern! 8 | 9 | ### Example: 10 | */ 11 | struct Game { 12 | static let sharedGame = Game() 13 | 14 | private init() { 15 | 16 | } 17 | } 18 | /*: 19 | ### Usage: 20 | */ 21 | let game = Game.sharedGame 22 | -------------------------------------------------------------------------------- /source/creational/_title.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Interpreter.xcplaygroundpage/timeline.xctimeline: -------------------------------------------------------------------------------- 1 | 2 | 4 | 5 | 9 | 10 | 11 | 12 | -------------------------------------------------------------------------------- /Behavioral.playground/contents.xcplayground: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | -------------------------------------------------------------------------------- /source/header.swift: -------------------------------------------------------------------------------- 1 | 2 | Design Patterns implemented in Swift 3.1 3 | ======================================== 4 | A short cheat-sheet with Xcode 8.3.2 Playground ([Design-Patterns.zip](https://raw.githubusercontent.com/zsergey/Design-Patterns-In-Swift/master/Design-Patterns.zip)). 5 | 6 | 👷 Project maintained by: [@zsergey](http://twitter.com/zsergey) (Sergey Zapuhlyak) 7 | 8 | 🚀 How to generate README, Playground and zip from source: [GENERATE.md](https://github.com/zsergey/Design-Patterns-In-Swift/blob/master/GENERATE.md) 9 | 10 | ## Table of Contents 11 | 12 | * [Behavioral](#behavioral) 13 | * [Creational](#creational) 14 | * [Structural](#structural) 15 | 16 | */ 17 | -------------------------------------------------------------------------------- /source/behavioral/Template-Method.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🐾 Template Method 3 | ---------- 4 | 5 | The template method pattern is used to define the program skeleton of an algorithm in an operation, deferring some steps to subclasses. It lets one redefine certain steps of an algorithm without changing the algorithm's structure. 6 | 7 | ### Example 8 | */ 9 | protocol WebsiteTemplate { 10 | func showPageContent() 11 | } 12 | 13 | extension WebsiteTemplate { 14 | func showPage() { 15 | print("Header") 16 | showPageContent() 17 | print("Footer") 18 | } 19 | } 20 | 21 | struct WelcomePage: WebsiteTemplate { 22 | func showPageContent() { 23 | print("Welcome") 24 | } 25 | } 26 | 27 | struct NewsPage: WebsiteTemplate { 28 | func showPageContent() { 29 | print("News") 30 | } 31 | } 32 | /*: 33 | ### Usage 34 | */ 35 | let welcomePage = WelcomePage() 36 | welcomePage.showPage() 37 | print("") 38 | 39 | let newsPage = NewsPage() 40 | newsPage.showPage() 41 | -------------------------------------------------------------------------------- /source/structural/Proxy.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | ☔ Proxy 3 | ------------------ 4 | 5 | The proxy pattern is used to provide a surrogate or placeholder object, which references an underlying object. 6 | 7 | ### Example 8 | */ 9 | protocol Project { 10 | func run() 11 | } 12 | 13 | struct RealProject: Project { 14 | var url: String 15 | 16 | func load() { 17 | print("Loading project from url \(url) ...") 18 | } 19 | 20 | init(url: String) { 21 | self.url = url 22 | load() 23 | } 24 | 25 | func run() { 26 | print("Running project \(url) ...") 27 | } 28 | } 29 | 30 | class ProxyProject: Project { 31 | var url: String 32 | var realProject: RealProject? 33 | 34 | func run() { 35 | if realProject == nil { 36 | realProject = RealProject(url: url) 37 | } 38 | realProject!.run() 39 | } 40 | 41 | init(url: String) { 42 | self.url = url 43 | } 44 | } 45 | /*: 46 | ### Usage 47 | */ 48 | var project = ProxyProject(url: "https://github.com/zsergey/realProject") 49 | project.run() 50 | -------------------------------------------------------------------------------- /Structural.playground/contents.xcplayground: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | -------------------------------------------------------------------------------- /Creational.playground/Pages/Singleton.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 💍 Singleton 13 | ------------ 14 | 15 | The singleton pattern ensures that only one object of a particular class is ever created. 16 | All further references to objects of the singleton class refer to the same underlying instance. 17 | There are very few applications, do not overuse this pattern! 18 | 19 | ### Example: 20 | */ 21 | struct Game { 22 | static let sharedGame = Game() 23 | 24 | private init() { 25 | 26 | } 27 | } 28 | /*: 29 | ### Usage: 30 | */ 31 | let game = Game.sharedGame 32 | -------------------------------------------------------------------------------- /source/creational/prototype.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🃏 Prototype 3 | ------------ 4 | 5 | The prototype pattern is used to instantiate a new object by copying all of the properties of an existing object, creating an independent clone. 6 | This practise is particularly useful when the construction of a new object is inefficient. 7 | 8 | ### Example 9 | */ 10 | protocol Copyable { 11 | func copy() -> Any 12 | } 13 | 14 | struct Project: Copyable { 15 | var id: Int 16 | var name: String 17 | var source: String 18 | 19 | func copy() -> Any { 20 | let object = Project(id: id, name: name, source: source) 21 | return object 22 | } 23 | } 24 | 25 | struct ProjectFactory { 26 | var project: Project 27 | func cloneProject() -> Project { 28 | return project.copy() as! Project 29 | } 30 | } 31 | /*: 32 | ### Usage 33 | */ 34 | let master = Project(id: 1, name: "Playground.swift", source: "let sourceCode = SourceCode()") 35 | let factory = ProjectFactory(project: master) 36 | let masterClone = factory.cloneProject() 37 | /*: 38 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Prototype) 39 | */ 40 | -------------------------------------------------------------------------------- /source/structural/facade.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🎁 Façade 3 | --------- 4 | 5 | The facade pattern is used to define a simplified interface to a more complex subsystem. 6 | 7 | ### Example 8 | */ 9 | class Job { 10 | func doJob() { 11 | print("Job is progress...") 12 | } 13 | } 14 | 15 | class BugTracker { 16 | var isActiveSprint = false 17 | 18 | func startSprint() { 19 | print("Sprint is active") 20 | isActiveSprint = true 21 | } 22 | 23 | func stopSprint() { 24 | print("Sprint is not active") 25 | isActiveSprint = false 26 | } 27 | } 28 | 29 | class Developer { 30 | func doJobBeforeDeadline(bugTracker: BugTracker) { 31 | if bugTracker.isActiveSprint { 32 | print("Developer is solving problems...") 33 | } else { 34 | print("Developer is reading the news...") 35 | } 36 | } 37 | } 38 | 39 | class Workflow { 40 | let developer = Developer() 41 | let job = Job() 42 | let bugTracker = BugTracker() 43 | func solveProblems() { 44 | job.doJob() 45 | bugTracker.startSprint() 46 | developer.doJobBeforeDeadline(bugTracker: bugTracker) 47 | } 48 | } 49 | /*: 50 | ### Usage 51 | */ 52 | let workflow = Workflow() 53 | workflow.solveProblems() 54 | -------------------------------------------------------------------------------- /source/structural/decorator.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🍧 Decorator 3 | ------------ 4 | 5 | The decorator pattern is used to extend or alter the functionality of objects at run- time by wrapping them in an object of a decorator class. 6 | This provides a flexible alternative to using inheritance to modify behaviour. 7 | 8 | ### Example 9 | */ 10 | protocol Developer { 11 | func makeJob() -> String 12 | } 13 | 14 | struct SwiftDeveloper: Developer { 15 | func makeJob() -> String { 16 | return "Write Swift code" 17 | } 18 | } 19 | 20 | class DeveloperDecorator: Developer { 21 | var developer: Developer 22 | func makeJob() -> String { 23 | return developer.makeJob() 24 | } 25 | init(developer: Developer) { 26 | self.developer = developer 27 | } 28 | } 29 | 30 | class SeniorSwiftDeveloper: DeveloperDecorator { 31 | let codeReview = "Make code review" 32 | override func makeJob() -> String { 33 | return super.makeJob() + " & " + codeReview 34 | } 35 | } 36 | 37 | class SwiftTeamLead: DeveloperDecorator { 38 | let sendWeekReport = "Send week report" 39 | override func makeJob() -> String { 40 | return super.makeJob() + " & " + sendWeekReport 41 | } 42 | } 43 | /*: 44 | ### Usage: 45 | */ 46 | let developer = SwiftTeamLead(developer: SeniorSwiftDeveloper(developer: SwiftDeveloper())) 47 | print(developer.makeJob()) 48 | -------------------------------------------------------------------------------- /source/behavioral/iterator.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🍫 Iterator 3 | ----------- 4 | 5 | The iterator pattern is used to provide a standard interface for traversing a collection of items in an aggregate object without the need to understand its underlying structure. 6 | 7 | ### Example: 8 | */ 9 | protocol Iterator { 10 | func hasNext() -> Bool 11 | mutating func next() -> String 12 | } 13 | 14 | protocol Collection { 15 | func getIterator() -> Iterator 16 | } 17 | 18 | struct SwiftDeveloper: Collection { 19 | var name: String 20 | var skills: [String] 21 | 22 | private struct SkillIterator: Iterator { 23 | var index: Int 24 | var data: [String] 25 | func hasNext() -> Bool { 26 | return index < data.count 27 | } 28 | mutating func next() -> String { 29 | let result = data[index] 30 | index = index + 1 31 | return result 32 | } 33 | } 34 | 35 | func getIterator() -> Iterator { 36 | return SkillIterator(index: 0, data: skills) 37 | } 38 | } 39 | /*: 40 | ### Usage 41 | */ 42 | let skills = ["Swift", "ObjC", "Sketch", "PM"] 43 | let swiftDeveloper = SwiftDeveloper(name: "Sergey Zapuhlyak", skills: skills) 44 | var iterator = swiftDeveloper.getIterator() 45 | print("Developer \(swiftDeveloper.name)") 46 | print("Skills") 47 | while iterator.hasNext() { 48 | print("\(iterator.next())") 49 | } 50 | -------------------------------------------------------------------------------- /source/structural/bridge.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🌉 Bridge 3 | ---------- 4 | 5 | The bridge pattern is used to separate the abstract elements of a class from the implementation details, providing the means to replace the implementation details without modifying the abstraction. 6 | 7 | ### Example 8 | */ 9 | protocol Developer { 10 | func writeCode() 11 | } 12 | 13 | protocol Program { 14 | var developer: Developer { get set } 15 | func develop() 16 | } 17 | 18 | struct SwiftDeveloper: Developer { 19 | func writeCode() { 20 | print("Swift Developer writes Swift code...") 21 | } 22 | } 23 | 24 | struct ObjCDeveloper: Developer { 25 | func writeCode() { 26 | print("ObjC Developer writes Objective-C code...") 27 | } 28 | } 29 | 30 | struct BankSystem: Program { 31 | var developer: Developer 32 | 33 | func develop() { 34 | print("Bank System development in progress...") 35 | developer.writeCode() 36 | } 37 | } 38 | 39 | struct StockExchange: Program { 40 | var developer: Developer 41 | 42 | func develop() { 43 | print("Stock Exchange development in progress...") 44 | developer.writeCode() 45 | } 46 | } 47 | /*: 48 | ### Usage 49 | */ 50 | let programs: [Program] = [BankSystem(developer: ObjCDeveloper()), 51 | StockExchange(developer: SwiftDeveloper())] 52 | for program in programs { 53 | program.develop() 54 | } 55 | -------------------------------------------------------------------------------- /source/behavioral/strategy.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 💡 Strategy 3 | ----------- 4 | 5 | The strategy pattern is used to create an interchangeable family of algorithms from which the required process is chosen at run-time. 6 | 7 | ### Example 8 | */ 9 | protocol Activity { 10 | func justDoIt() 11 | } 12 | 13 | struct Coding: Activity { 14 | func justDoIt() { 15 | print("Writing code...") 16 | } 17 | } 18 | 19 | struct Reading: Activity { 20 | func justDoIt() { 21 | print("Reading book...") 22 | } 23 | } 24 | 25 | struct Sleeping: Activity { 26 | func justDoIt() { 27 | print("Sleeping...") 28 | } 29 | } 30 | 31 | struct Training: Activity { 32 | func justDoIt() { 33 | print("Training...") 34 | } 35 | } 36 | 37 | struct Developer { 38 | var activity: Activity 39 | 40 | func executeActivity() { 41 | activity.justDoIt() 42 | } 43 | } 44 | /*: 45 | ### Usage 46 | */ 47 | var developer = Developer(activity: Sleeping()) 48 | developer.executeActivity() 49 | 50 | developer.activity = Training() 51 | developer.executeActivity() 52 | 53 | developer.activity = Coding() 54 | developer.executeActivity() 55 | 56 | developer.activity = Reading() 57 | developer.executeActivity() 58 | 59 | developer.activity = Sleeping() 60 | developer.executeActivity() 61 | /*: 62 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Strategy) 63 | */ 64 | -------------------------------------------------------------------------------- /source/creational/factory.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🏭 Factory Method 3 | ----------------- 4 | 5 | The factory pattern is used to replace class constructors, abstracting the process of object generation so that the type of the object instantiated can be determined at run-time. 6 | 7 | ### Example 8 | */ 9 | protocol Developer { 10 | func writeCode() 11 | } 12 | 13 | struct ObjCDeveloper: Developer { 14 | func writeCode() { 15 | print("ObjC developer writes Objective C code...") 16 | } 17 | } 18 | 19 | struct SwiftDeveloper: Developer { 20 | func writeCode() { 21 | print("Swift developer writes Swift code...") 22 | } 23 | } 24 | 25 | protocol DeveloperFactory { 26 | func newDeveloper() -> Developer 27 | } 28 | 29 | struct ObjCDeveloperFactory: DeveloperFactory { 30 | func newDeveloper() -> Developer { 31 | return ObjCDeveloper() 32 | } 33 | } 34 | 35 | struct SwiftDeveloperFactory: DeveloperFactory { 36 | func newDeveloper() -> Developer { 37 | return SwiftDeveloper() 38 | } 39 | } 40 | 41 | enum Languages { 42 | case objC 43 | case swift 44 | 45 | var factory: DeveloperFactory { 46 | switch self { 47 | case .objC: 48 | return ObjCDeveloperFactory() 49 | case .swift: 50 | return SwiftDeveloperFactory() 51 | } 52 | } 53 | } 54 | /*: 55 | ### Usage 56 | */ 57 | let developer = Languages.swift.factory.newDeveloper() 58 | developer.writeCode() 59 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Proxy.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | ☔ Proxy 13 | ------------------ 14 | 15 | The proxy pattern is used to provide a surrogate or placeholder object, which references an underlying object. 16 | 17 | ### Example 18 | */ 19 | protocol Project { 20 | func run() 21 | } 22 | 23 | struct RealProject: Project { 24 | var url: String 25 | 26 | func load() { 27 | print("Loading project from url \(url) ...") 28 | } 29 | 30 | init(url: String) { 31 | self.url = url 32 | load() 33 | } 34 | 35 | func run() { 36 | print("Running project \(url) ...") 37 | } 38 | } 39 | 40 | class ProxyProject: Project { 41 | var url: String 42 | var realProject: RealProject? 43 | 44 | func run() { 45 | if realProject == nil { 46 | realProject = RealProject(url: url) 47 | } 48 | realProject!.run() 49 | } 50 | 51 | init(url: String) { 52 | self.url = url 53 | } 54 | } 55 | /*: 56 | ### Usage 57 | */ 58 | var project = ProxyProject(url: "https://github.com/zsergey/realProject") 59 | project.run() 60 | -------------------------------------------------------------------------------- /source/structural/composite.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🌿 Composite 3 | ------------- 4 | 5 | The composite pattern is used to create hierarchical, recursive tree structures of related objects where any element of the structure may be accessed and utilised in a standard manner. 6 | 7 | ### Example 8 | */ 9 | protocol Developer { 10 | func writeCode() 11 | } 12 | 13 | protocol Team { 14 | var developers: [Developer] { set get } 15 | func addDeveloper(developer: Developer) 16 | func createProject() 17 | } 18 | 19 | struct SwiftDeveloper: Developer{ 20 | func writeCode() { 21 | print("Swift Developer writes Swift code...") 22 | } 23 | } 24 | 25 | struct ObjCDeveloper: Developer{ 26 | func writeCode() { 27 | print("ObjC Developer writes Objective-C code...") 28 | } 29 | } 30 | 31 | class BankTeam: Team { 32 | var developers = [Developer]() 33 | 34 | func addDeveloper(developer: Developer) { 35 | developers.append(developer) 36 | } 37 | 38 | func createProject() { 39 | for developer in developers { 40 | developer.writeCode() 41 | } 42 | } 43 | } 44 | /*: 45 | ### Usage: 46 | */ 47 | let team = BankTeam() 48 | team.addDeveloper(developer: ObjCDeveloper()) 49 | team.addDeveloper(developer: ObjCDeveloper()) 50 | team.addDeveloper(developer: ObjCDeveloper()) 51 | team.addDeveloper(developer: ObjCDeveloper()) 52 | team.addDeveloper(developer: SwiftDeveloper()) 53 | team.createProject() 54 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Template-method.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🐾 Template Method 13 | ---------- 14 | 15 | The template method pattern is used to define the program skeleton of an algorithm in an operation, deferring some steps to subclasses. It lets one redefine certain steps of an algorithm without changing the algorithm's structure. 16 | 17 | ### Example 18 | */ 19 | protocol WebsiteTemplate { 20 | func showPageContent() 21 | } 22 | 23 | extension WebsiteTemplate { 24 | func showPage() { 25 | print("Header") 26 | showPageContent() 27 | print("Footer") 28 | } 29 | } 30 | 31 | struct WelcomePage: WebsiteTemplate { 32 | func showPageContent() { 33 | print("Welcome") 34 | } 35 | } 36 | 37 | struct NewsPage: WebsiteTemplate { 38 | func showPageContent() { 39 | print("News") 40 | } 41 | } 42 | /*: 43 | ### Usage 44 | */ 45 | let welcomePage = WelcomePage() 46 | welcomePage.showPage() 47 | print("") 48 | 49 | let newsPage = NewsPage() 50 | newsPage.showPage() 51 | -------------------------------------------------------------------------------- /source/behavioral/memento.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 💾 Memento 3 | ---------- 4 | 5 | The memento pattern is used to capture the current state of an object and store it in such a manner that it can be restored at a later time without breaking the rules of encapsulation. 6 | 7 | ### Example 8 | */ 9 | struct Project { 10 | var version: String 11 | var code: String 12 | 13 | func save() -> Save { 14 | return Save(version: version, code: code) 15 | } 16 | 17 | mutating func load(save: Save) { 18 | version = save.version 19 | code = save.code 20 | } 21 | 22 | func description() -> String { 23 | return "Project version = \(version): \n'\(code)'\n" 24 | } 25 | } 26 | 27 | struct Save { 28 | var version: String 29 | var code: String 30 | } 31 | 32 | struct GithubRepo { 33 | var save: Save 34 | } 35 | /*: 36 | ### Usage 37 | */ 38 | print("Creating new project. Version 1.0") 39 | var project = Project(version: "1.0", code: "let index = 0") 40 | print(project.description()) 41 | 42 | print("Saving current version to github") 43 | let github = GithubRepo(save: project.save()) 44 | 45 | print("Updating project to Version 1.1") 46 | print("Writing poor code...") 47 | print("Set version 1.1") 48 | project.version = "1.1" 49 | project.code = "let index = 0\nindex = 5" 50 | print(project.description()) 51 | 52 | print("Something went wrong") 53 | print("Rolling back to Version 1.0") 54 | 55 | project.load(save: github.save) 56 | print("Project after rollback") 57 | print(project.description()) 58 | -------------------------------------------------------------------------------- /source/structural/adapter.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🔌 Adapter 3 | ---------- 4 | 5 | The adapter pattern is used to provide a link between two otherwise incompatible types by wrapping the "adaptee" with a class that supports the interface required by the client. 6 | 7 | ### Example 8 | */ 9 | protocol Database { 10 | func insert() 11 | func update() 12 | func select() 13 | func remove() 14 | } 15 | 16 | class SwiftApp { 17 | func saveObject() { 18 | print("Saving Swift Object...") 19 | } 20 | 21 | func updateObject() { 22 | print("Updating Swift Object...") 23 | } 24 | 25 | func loadObject() { 26 | print("Loading Swift Object...") 27 | } 28 | 29 | func deleteObject() { 30 | print("Deleting Swift Object...") 31 | } 32 | } 33 | 34 | class AdapterSwiftAppToDatabase: SwiftApp, Database { 35 | func insert() { 36 | saveObject() 37 | } 38 | 39 | func update() { 40 | updateObject() 41 | } 42 | 43 | func select() { 44 | loadObject() 45 | } 46 | 47 | func remove() { 48 | deleteObject() 49 | } 50 | } 51 | 52 | struct DatabaseManager { 53 | var database: Database 54 | func run() { 55 | database.insert() 56 | database.update() 57 | database.select() 58 | database.remove() 59 | } 60 | } 61 | /*: 62 | ### Usage 63 | */ 64 | let databaseManager = DatabaseManager(database: AdapterSwiftAppToDatabase()) 65 | databaseManager.run() 66 | /*: 67 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Adapter) 68 | */ 69 | -------------------------------------------------------------------------------- /source/behavioral/state.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🐉 State 3 | --------- 4 | 5 | The state pattern is used to alter the behaviour of an object as its internal state changes. 6 | The pattern allows the class for an object to apparently change at run-time. 7 | 8 | ### Example 9 | */ 10 | protocol Activity { 11 | func justDoIt() 12 | } 13 | 14 | struct Coding: Activity { 15 | func justDoIt() { 16 | print("Writing code...") 17 | } 18 | } 19 | 20 | struct Reading: Activity { 21 | func justDoIt() { 22 | print("Reading book...") 23 | } 24 | } 25 | 26 | struct Sleeping: Activity { 27 | func justDoIt() { 28 | print("Sleeping...") 29 | } 30 | } 31 | 32 | struct Training: Activity { 33 | func justDoIt() { 34 | print("Training...") 35 | } 36 | } 37 | 38 | struct Developer { 39 | var activity: Activity 40 | 41 | mutating func changeActivity() { 42 | if let _ = activity as? Sleeping { 43 | activity = Training() 44 | } else if let _ = activity as? Training { 45 | activity = Coding() 46 | } else if let _ = activity as? Coding { 47 | activity = Reading() 48 | } else if let _ = activity as? Reading { 49 | activity = Sleeping() 50 | } 51 | } 52 | 53 | func justDoIt() { 54 | activity.justDoIt() 55 | } 56 | } 57 | /*: 58 | ### Usage 59 | */ 60 | let activity = Sleeping() 61 | var developer = Developer(activity: activity) 62 | for i in 0..<10 { 63 | developer.justDoIt() 64 | developer.changeActivity() 65 | } 66 | /*: 67 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-State) 68 | */ 69 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Facade.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🎁 Façade 13 | --------- 14 | 15 | The facade pattern is used to define a simplified interface to a more complex subsystem. 16 | 17 | ### Example 18 | */ 19 | class Job { 20 | func doJob() { 21 | print("Job is progress...") 22 | } 23 | } 24 | 25 | class BugTracker { 26 | var isActiveSprint = false 27 | 28 | func startSprint() { 29 | print("Sprint is active") 30 | isActiveSprint = true 31 | } 32 | 33 | func stopSprint() { 34 | print("Sprint is not active") 35 | isActiveSprint = false 36 | } 37 | } 38 | 39 | class Developer { 40 | func doJobBeforeDeadline(bugTracker: BugTracker) { 41 | if bugTracker.isActiveSprint { 42 | print("Developer is solving problems...") 43 | } else { 44 | print("Developer is reading the news...") 45 | } 46 | } 47 | } 48 | 49 | class Workflow { 50 | let developer = Developer() 51 | let job = Job() 52 | let bugTracker = BugTracker() 53 | func solveProblems() { 54 | job.doJob() 55 | bugTracker.startSprint() 56 | developer.doJobBeforeDeadline(bugTracker: bugTracker) 57 | } 58 | } 59 | /*: 60 | ### Usage 61 | */ 62 | let workflow = Workflow() 63 | workflow.solveProblems() 64 | -------------------------------------------------------------------------------- /Creational.playground/Pages/Prototype.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🃏 Prototype 13 | ------------ 14 | 15 | The prototype pattern is used to instantiate a new object by copying all of the properties of an existing object, creating an independent clone. 16 | This practise is particularly useful when the construction of a new object is inefficient. 17 | 18 | ### Example 19 | */ 20 | protocol Copyable { 21 | func copy() -> Any 22 | } 23 | 24 | struct Project: Copyable { 25 | var id: Int 26 | var name: String 27 | var source: String 28 | 29 | func copy() -> Any { 30 | let object = Project(id: id, name: name, source: source) 31 | return object 32 | } 33 | } 34 | 35 | struct ProjectFactory { 36 | var project: Project 37 | func cloneProject() -> Project { 38 | return project.copy() as! Project 39 | } 40 | } 41 | /*: 42 | ### Usage 43 | */ 44 | let master = Project(id: 1, name: "Playground.swift", source: "let sourceCode = SourceCode()") 45 | let factory = ProjectFactory(project: master) 46 | let masterClone = factory.cloneProject() 47 | /*: 48 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Prototype) 49 | */ 50 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Decorator.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🍧 Decorator 13 | ------------ 14 | 15 | The decorator pattern is used to extend or alter the functionality of objects at run- time by wrapping them in an object of a decorator class. 16 | This provides a flexible alternative to using inheritance to modify behaviour. 17 | 18 | ### Example 19 | */ 20 | protocol Developer { 21 | func makeJob() -> String 22 | } 23 | 24 | struct SwiftDeveloper: Developer { 25 | func makeJob() -> String { 26 | return "Write Swift code" 27 | } 28 | } 29 | 30 | class DeveloperDecorator: Developer { 31 | var developer: Developer 32 | func makeJob() -> String { 33 | return developer.makeJob() 34 | } 35 | init(developer: Developer) { 36 | self.developer = developer 37 | } 38 | } 39 | 40 | class SeniorSwiftDeveloper: DeveloperDecorator { 41 | let codeReview = "Make code review" 42 | override func makeJob() -> String { 43 | return super.makeJob() + " & " + codeReview 44 | } 45 | } 46 | 47 | class SwiftTeamLead: DeveloperDecorator { 48 | let sendWeekReport = "Send week report" 49 | override func makeJob() -> String { 50 | return super.makeJob() + " & " + sendWeekReport 51 | } 52 | } 53 | /*: 54 | ### Usage: 55 | */ 56 | let developer = SwiftTeamLead(developer: SeniorSwiftDeveloper(developer: SwiftDeveloper())) 57 | print(developer.makeJob()) 58 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Bridge.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🌉 Bridge 13 | ---------- 14 | 15 | The bridge pattern is used to separate the abstract elements of a class from the implementation details, providing the means to replace the implementation details without modifying the abstraction. 16 | 17 | ### Example 18 | */ 19 | protocol Developer { 20 | func writeCode() 21 | } 22 | 23 | protocol Program { 24 | var developer: Developer { get set } 25 | func develop() 26 | } 27 | 28 | struct SwiftDeveloper: Developer { 29 | func writeCode() { 30 | print("Swift Developer writes Swift code...") 31 | } 32 | } 33 | 34 | struct ObjCDeveloper: Developer { 35 | func writeCode() { 36 | print("ObjC Developer writes Objective-C code...") 37 | } 38 | } 39 | 40 | struct BankSystem: Program { 41 | var developer: Developer 42 | 43 | func develop() { 44 | print("Bank System development in progress...") 45 | developer.writeCode() 46 | } 47 | } 48 | 49 | struct StockExchange: Program { 50 | var developer: Developer 51 | 52 | func develop() { 53 | print("Stock Exchange development in progress...") 54 | developer.writeCode() 55 | } 56 | } 57 | /*: 58 | ### Usage 59 | */ 60 | let programs: [Program] = [BankSystem(developer: ObjCDeveloper()), 61 | StockExchange(developer: SwiftDeveloper())] 62 | for program in programs { 63 | program.develop() 64 | } 65 | -------------------------------------------------------------------------------- /Design-Patterns.playground/playground.xcworkspace/xcshareddata/Design-Patterns.xccheckout: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | IDESourceControlProjectFavoriteDictionaryKey 6 | 7 | IDESourceControlProjectIdentifier 8 | 6E6A675F-9997-43AE-BB1C-8E4B69F9AD36 9 | IDESourceControlProjectName 10 | Design-Patterns 11 | IDESourceControlProjectOriginsDictionary 12 | 13 | C96876E4909DB6FA99FAEC5AD77808104236AA02 14 | https://github.com/ochococo/Design-Patterns-In-Swift.git 15 | 16 | IDESourceControlProjectPath 17 | Design-Patterns.playground 18 | IDESourceControlProjectRelativeInstallPathDictionary 19 | 20 | C96876E4909DB6FA99FAEC5AD77808104236AA02 21 | .. 22 | 23 | IDESourceControlProjectURL 24 | https://github.com/ochococo/Design-Patterns-In-Swift.git 25 | IDESourceControlProjectVersion 26 | 111 27 | IDESourceControlProjectWCCIdentifier 28 | C96876E4909DB6FA99FAEC5AD77808104236AA02 29 | IDESourceControlProjectWCConfigurations 30 | 31 | 32 | IDESourceControlRepositoryExtensionIdentifierKey 33 | public.vcs.git 34 | IDESourceControlWCCIdentifierKey 35 | C96876E4909DB6FA99FAEC5AD77808104236AA02 36 | IDESourceControlWCCName 37 | Design-Patterns-In-Swift 38 | 39 | 40 | 41 | 42 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Composite.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🌿 Composite 13 | ------------- 14 | 15 | The composite pattern is used to create hierarchical, recursive tree structures of related objects where any element of the structure may be accessed and utilised in a standard manner. 16 | 17 | ### Example 18 | */ 19 | protocol Developer { 20 | func writeCode() 21 | } 22 | 23 | protocol Team { 24 | var developers: [Developer] { set get } 25 | func addDeveloper(developer: Developer) 26 | func createProject() 27 | } 28 | 29 | struct SwiftDeveloper: Developer{ 30 | func writeCode() { 31 | print("Swift Developer writes Swift code...") 32 | } 33 | } 34 | 35 | struct ObjCDeveloper: Developer{ 36 | func writeCode() { 37 | print("ObjC Developer writes Objective-C code...") 38 | } 39 | } 40 | 41 | class BankTeam: Team { 42 | var developers = [Developer]() 43 | 44 | func addDeveloper(developer: Developer) { 45 | developers.append(developer) 46 | } 47 | 48 | func createProject() { 49 | for developer in developers { 50 | developer.writeCode() 51 | } 52 | } 53 | } 54 | /*: 55 | ### Usage: 56 | */ 57 | let team = BankTeam() 58 | team.addDeveloper(developer: ObjCDeveloper()) 59 | team.addDeveloper(developer: ObjCDeveloper()) 60 | team.addDeveloper(developer: ObjCDeveloper()) 61 | team.addDeveloper(developer: ObjCDeveloper()) 62 | team.addDeveloper(developer: SwiftDeveloper()) 63 | team.createProject() 64 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Iterator.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🍫 Iterator 13 | ----------- 14 | 15 | The iterator pattern is used to provide a standard interface for traversing a collection of items in an aggregate object without the need to understand its underlying structure. 16 | 17 | ### Example: 18 | */ 19 | protocol Iterator { 20 | func hasNext() -> Bool 21 | mutating func next() -> String 22 | } 23 | 24 | protocol Collection { 25 | func getIterator() -> Iterator 26 | } 27 | 28 | struct SwiftDeveloper: Collection { 29 | var name: String 30 | var skills: [String] 31 | 32 | private struct SkillIterator: Iterator { 33 | var index: Int 34 | var data: [String] 35 | func hasNext() -> Bool { 36 | return index < data.count 37 | } 38 | mutating func next() -> String { 39 | let result = data[index] 40 | index = index + 1 41 | return result 42 | } 43 | } 44 | 45 | func getIterator() -> Iterator { 46 | return SkillIterator(index: 0, data: skills) 47 | } 48 | } 49 | /*: 50 | ### Usage 51 | */ 52 | let skills = ["Swift", "ObjC", "Sketch", "PM"] 53 | let swiftDeveloper = SwiftDeveloper(name: "Sergey Zapuhlyak", skills: skills) 54 | var iterator = swiftDeveloper.getIterator() 55 | print("Developer \(swiftDeveloper.name)") 56 | print("Skills") 57 | while iterator.hasNext() { 58 | print("\(iterator.next())") 59 | } 60 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Strategy.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 💡 Strategy 13 | ----------- 14 | 15 | The strategy pattern is used to create an interchangeable family of algorithms from which the required process is chosen at run-time. 16 | 17 | ### Example 18 | */ 19 | protocol Activity { 20 | func justDoIt() 21 | } 22 | 23 | struct Coding: Activity { 24 | func justDoIt() { 25 | print("Writing code...") 26 | } 27 | } 28 | 29 | struct Reading: Activity { 30 | func justDoIt() { 31 | print("Reading book...") 32 | } 33 | } 34 | 35 | struct Sleeping: Activity { 36 | func justDoIt() { 37 | print("Sleeping...") 38 | } 39 | } 40 | 41 | struct Training: Activity { 42 | func justDoIt() { 43 | print("Training...") 44 | } 45 | } 46 | 47 | struct Developer { 48 | var activity: Activity 49 | 50 | func executeActivity() { 51 | activity.justDoIt() 52 | } 53 | } 54 | /*: 55 | ### Usage 56 | */ 57 | var developer = Developer(activity: Sleeping()) 58 | developer.executeActivity() 59 | 60 | developer.activity = Training() 61 | developer.executeActivity() 62 | 63 | developer.activity = Coding() 64 | developer.executeActivity() 65 | 66 | developer.activity = Reading() 67 | developer.executeActivity() 68 | 69 | developer.activity = Sleeping() 70 | developer.executeActivity() 71 | /*: 72 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Strategy) 73 | */ 74 | -------------------------------------------------------------------------------- /source/structural/flyweight.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | ## 🍃 Flyweight 3 | The flyweight pattern is used to minimize memory usage or computational expenses by sharing as much as possible with other similar objects. 4 | ### Example 5 | */ 6 | protocol Developer { 7 | func writeCode() 8 | } 9 | 10 | struct SwiftDeveloper: Developer { 11 | func writeCode() { 12 | print("Swift Developer writes Swift code...") 13 | } 14 | } 15 | 16 | struct ObjCDeveloper: Developer { 17 | func writeCode() { 18 | print("ObjC Developer writes Objective-C code...") 19 | } 20 | } 21 | 22 | enum Languages: String { 23 | case Swift 24 | case ObjC 25 | 26 | var description: String { 27 | return self.rawValue 28 | } 29 | } 30 | 31 | struct DeveloperFactory { 32 | private var developers = [String: Developer]() 33 | 34 | mutating func developer(by language: Languages) -> Developer { 35 | if let value = developers[language.description] { 36 | return value 37 | } else { 38 | var value: Developer? = nil 39 | print("Hiring \(language.description) developer ") 40 | switch language { 41 | case .Swift: 42 | value = SwiftDeveloper() 43 | case .ObjC: 44 | value = ObjCDeveloper() 45 | } 46 | developers[language.description] = value 47 | return value! 48 | } 49 | } 50 | } 51 | /*: 52 | ### Usage 53 | */ 54 | var developerFactory = DeveloperFactory() 55 | var developers = [Developer]() 56 | developers.append(developerFactory.developer(by: .Swift)) 57 | developers.append(developerFactory.developer(by: .Swift)) 58 | developers.append(developerFactory.developer(by: .Swift)) 59 | developers.append(developerFactory.developer(by: .ObjC)) 60 | developers.append(developerFactory.developer(by: .ObjC)) 61 | developers.append(developerFactory.developer(by: .ObjC)) 62 | for developer in developers { 63 | developer.writeCode() 64 | } 65 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Adapter.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🔌 Adapter 13 | ---------- 14 | 15 | The adapter pattern is used to provide a link between two otherwise incompatible types by wrapping the "adaptee" with a class that supports the interface required by the client. 16 | 17 | ### Example 18 | */ 19 | protocol Database { 20 | func insert() 21 | func update() 22 | func select() 23 | func remove() 24 | } 25 | 26 | class SwiftApp { 27 | func saveObject() { 28 | print("Saving Swift Object...") 29 | } 30 | 31 | func updateObject() { 32 | print("Updating Swift Object...") 33 | } 34 | 35 | func loadObject() { 36 | print("Loading Swift Object...") 37 | } 38 | 39 | func deleteObject() { 40 | print("Deleting Swift Object...") 41 | } 42 | } 43 | 44 | class AdapterSwiftAppToDatabase: SwiftApp, Database { 45 | func insert() { 46 | saveObject() 47 | } 48 | 49 | func update() { 50 | updateObject() 51 | } 52 | 53 | func select() { 54 | loadObject() 55 | } 56 | 57 | func remove() { 58 | deleteObject() 59 | } 60 | } 61 | 62 | struct DatabaseManager { 63 | var database: Database 64 | func run() { 65 | database.insert() 66 | database.update() 67 | database.select() 68 | database.remove() 69 | } 70 | } 71 | /*: 72 | ### Usage 73 | */ 74 | let databaseManager = DatabaseManager(database: AdapterSwiftAppToDatabase()) 75 | databaseManager.run() 76 | /*: 77 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Adapter) 78 | */ 79 | -------------------------------------------------------------------------------- /source/behavioral/interpreter.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🎶 Interpreter 3 | -------------- 4 | 5 | The interpreter pattern is used to evaluate sentences in a language. 6 | 7 | ### Example 8 | */ 9 | protocol Expression { 10 | func interpret(_ context: String) -> Bool 11 | } 12 | 13 | struct AndExpression: Expression { 14 | var expression1: Expression 15 | var expression2: Expression 16 | 17 | func interpret(_ context: String) -> Bool { 18 | return expression1.interpret(context) && expression2.interpret(context) 19 | } 20 | } 21 | 22 | struct OrExpression: Expression { 23 | var expression1: Expression 24 | var expression2: Expression 25 | 26 | func interpret(_ context: String) -> Bool { 27 | return expression1.interpret(context) || expression2.interpret(context) 28 | } 29 | } 30 | 31 | struct TerminalExpression: Expression { 32 | var data: String 33 | 34 | func interpret(_ context: String) -> Bool { 35 | return context.contains(data) 36 | } 37 | } 38 | /*: 39 | ### Usage 40 | */ 41 | struct Interpreter { 42 | static func getAppleExpression() -> Expression { 43 | let swift = TerminalExpression(data: "Swift") 44 | let objC = TerminalExpression(data: "Objective-C") 45 | return OrExpression(expression1: objC, expression2: swift) 46 | } 47 | 48 | static func getJavaEEExpression() -> Expression { 49 | let java = TerminalExpression(data: "Java") 50 | let spring = TerminalExpression(data: "Spring") 51 | return AndExpression(expression1: java, expression2: spring) 52 | } 53 | } 54 | 55 | let appleExpression = Interpreter.getAppleExpression() 56 | let javaExpression = Interpreter.getJavaEEExpression() 57 | print("Is Developer an Apple Developer \(appleExpression.interpret("Swift"))") 58 | print("Does developer knows Java EE \(javaExpression.interpret("Java Spring"))") 59 | /*: 60 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Interpreter) 61 | */ 62 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Memento.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 💾 Memento 13 | ---------- 14 | 15 | The memento pattern is used to capture the current state of an object and store it in such a manner that it can be restored at a later time without breaking the rules of encapsulation. 16 | 17 | ### Example 18 | */ 19 | struct Project { 20 | var version: String 21 | var code: String 22 | 23 | func save() -> Save { 24 | return Save(version: version, code: code) 25 | } 26 | 27 | mutating func load(save: Save) { 28 | version = save.version 29 | code = save.code 30 | } 31 | 32 | func description() -> String { 33 | return "Project version = \(version): \n'\(code)'\n" 34 | } 35 | } 36 | 37 | struct Save { 38 | var version: String 39 | var code: String 40 | } 41 | 42 | struct GithubRepo { 43 | var save: Save 44 | } 45 | /*: 46 | ### Usage 47 | */ 48 | print("Creating new project. Version 1.0") 49 | var project = Project(version: "1.0", code: "let index = 0") 50 | print(project.description()) 51 | 52 | print("Saving current version to github") 53 | let github = GithubRepo(save: project.save()) 54 | 55 | print("Updating project to Version 1.1") 56 | print("Writing poor code...") 57 | print("Set version 1.1") 58 | project.version = "1.1" 59 | project.code = "let index = 0\nindex = 5" 60 | print(project.description()) 61 | 62 | print("Something went wrong") 63 | print("Rolling back to Version 1.0") 64 | 65 | project.load(save: github.save) 66 | print("Project after rollback") 67 | print(project.description()) 68 | -------------------------------------------------------------------------------- /Creational.playground/Pages/Factory.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🏭 Factory Method 13 | ----------------- 14 | 15 | The factory pattern is used to replace class constructors, abstracting the process of object generation so that the type of the object instantiated can be determined at run-time. 16 | 17 | ### Example 18 | */ 19 | protocol Developer { 20 | func writeCode() 21 | } 22 | 23 | struct ObjCDeveloper: Developer { 24 | func writeCode() { 25 | print("ObjC developer writes Objective C code...") 26 | } 27 | } 28 | 29 | struct SwiftDeveloper: Developer { 30 | func writeCode() { 31 | print("Swift developer writes Swift code...") 32 | } 33 | } 34 | 35 | protocol DeveloperFactory { 36 | func newDeveloper() -> Developer 37 | } 38 | 39 | struct ObjCDeveloperFactory: DeveloperFactory { 40 | func newDeveloper() -> Developer { 41 | return ObjCDeveloper() 42 | } 43 | } 44 | 45 | struct SwiftDeveloperFactory: DeveloperFactory { 46 | func newDeveloper() -> Developer { 47 | return SwiftDeveloper() 48 | } 49 | } 50 | 51 | enum Languages { 52 | case objC 53 | case swift 54 | 55 | var factory: DeveloperFactory { 56 | switch self { 57 | case .objC: 58 | return ObjCDeveloperFactory() 59 | case .swift: 60 | return SwiftDeveloperFactory() 61 | } 62 | } 63 | } 64 | /*: 65 | ### Usage 66 | */ 67 | let developer = Languages.swift.factory.newDeveloper() 68 | developer.writeCode() 69 | -------------------------------------------------------------------------------- /generate-playground.sh: -------------------------------------------------------------------------------- 1 | #!/bin/bash 2 | 3 | cleanThisMessForReadme () { 4 | 5 | FILENAME=$1 6 | 7 | { rm $FILENAME && awk '{gsub("\\*/", "\n```swift\n", $0); print}' > $FILENAME; } < $FILENAME 8 | { rm $FILENAME && awk '{gsub("\\*//\\*:", "", $0); print}' > $FILENAME; } < $FILENAME 9 | { rm $FILENAME && awk '{gsub("/\\*:", "```\n", $0); print}' > $FILENAME; } < $FILENAME 10 | { rm $FILENAME && awk '{gsub("//\\*:", "", $0); print}' > $FILENAME; } < $FILENAME 11 | { rm $FILENAME && awk '{gsub("//:", "", $0); print}' > $FILENAME; } < $FILENAME 12 | { rm $FILENAME && awk 'NR>1{print buf}{buf = $0}' > $FILENAME; } < $FILENAME 13 | } 14 | 15 | makePlayground () { 16 | for i in $( ls source/$1 ); 17 | do 18 | 19 | if [[ $i == *"title"* ]]; then 20 | continue 21 | fi 22 | 23 | cat source/$1/_title.swift source/$1/$i > $i 24 | baseName=`echo $i | cut -d "." -f 1` 25 | 26 | cp $i ./$1.playground/Pages/$baseName.xcplaygroundpage/Contents.swift 27 | rm $i 28 | 29 | done 30 | } 31 | 32 | cat source/behavioral/* > ./Behavioral.swift 33 | cat source/creational/* > ./Creational.swift 34 | cat source/structural/* > ./Structural.swift 35 | 36 | cp ./Behavioral.swift ./Design-Patterns.playground/Pages/Behavioral.xcplaygroundpage/Contents.swift 37 | cp ./Creational.swift ./Design-Patterns.playground/Pages/Creational.xcplaygroundpage/Contents.swift 38 | cp ./Structural.swift ./Design-Patterns.playground/Pages/Structural.xcplaygroundpage/Contents.swift 39 | 40 | cat source/header.swift source/*/* source/footer.swift > ./contents.swift 41 | 42 | cleanThisMessForReadme ./contents.swift 43 | 44 | cp ./contents.swift ./README.md 45 | 46 | #zip -r -X Design-Patterns.playground.zip ./Design-Patterns.playground 47 | 48 | rm ./Behavioral.swift 49 | rm ./Creational.swift 50 | rm ./Structural.swift 51 | rm ./contents.swift 52 | 53 | makePlayground Behavioral 54 | makePlayground Creational 55 | makePlayground Structural 56 | 57 | zip -r -X Design-Patterns.zip ./Behavioral.playground ./Creational.playground ./Structural.playground 58 | 59 | 60 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/State.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🐉 State 13 | --------- 14 | 15 | The state pattern is used to alter the behaviour of an object as its internal state changes. 16 | The pattern allows the class for an object to apparently change at run-time. 17 | 18 | ### Example 19 | */ 20 | protocol Activity { 21 | func justDoIt() 22 | } 23 | 24 | struct Coding: Activity { 25 | func justDoIt() { 26 | print("Writing code...") 27 | } 28 | } 29 | 30 | struct Reading: Activity { 31 | func justDoIt() { 32 | print("Reading book...") 33 | } 34 | } 35 | 36 | struct Sleeping: Activity { 37 | func justDoIt() { 38 | print("Sleeping...") 39 | } 40 | } 41 | 42 | struct Training: Activity { 43 | func justDoIt() { 44 | print("Training...") 45 | } 46 | } 47 | 48 | struct Developer { 49 | var activity: Activity 50 | 51 | mutating func changeActivity() { 52 | if let _ = activity as? Sleeping { 53 | activity = Training() 54 | } else if let _ = activity as? Training { 55 | activity = Coding() 56 | } else if let _ = activity as? Coding { 57 | activity = Reading() 58 | } else if let _ = activity as? Reading { 59 | activity = Sleeping() 60 | } 61 | } 62 | 63 | func justDoIt() { 64 | activity.justDoIt() 65 | } 66 | } 67 | /*: 68 | ### Usage 69 | */ 70 | let activity = Sleeping() 71 | var developer = Developer(activity: activity) 72 | for i in 0..<10 { 73 | developer.justDoIt() 74 | developer.changeActivity() 75 | } 76 | /*: 77 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-State) 78 | */ 79 | -------------------------------------------------------------------------------- /source/behavioral/command.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 👫 Command 3 | ---------- 4 | 5 | The command pattern is used to express a request, including the call to be made and all of its required parameters, in a command object. The command may then be executed immediately or held for later use. 6 | 7 | ### Example: 8 | */ 9 | struct Database { 10 | func insert() { 11 | print("Inserting record...") 12 | } 13 | 14 | func update() { 15 | print("Updating record...") 16 | } 17 | 18 | func select() { 19 | print("Reading record...") 20 | } 21 | 22 | func delete() { 23 | print("Deleting record...") 24 | } 25 | } 26 | 27 | protocol Command { 28 | var database: Database { set get } 29 | func execute() 30 | } 31 | 32 | struct InsertCommand: Command { 33 | internal var database: Database 34 | 35 | func execute() { 36 | database.insert() 37 | } 38 | } 39 | 40 | struct UpdateCommand: Command { 41 | internal var database: Database 42 | 43 | func execute() { 44 | database.update() 45 | } 46 | } 47 | 48 | struct SelectCommand: Command { 49 | internal var database: Database 50 | 51 | func execute() { 52 | database.select() 53 | } 54 | } 55 | 56 | struct DeleteCommand: Command { 57 | internal var database: Database 58 | 59 | func execute() { 60 | database.delete() 61 | } 62 | } 63 | 64 | struct Developer { 65 | var insert, update, select, delete: Command 66 | 67 | func insertRecord() { 68 | insert.execute() 69 | } 70 | 71 | func updateRecord() { 72 | update.execute() 73 | } 74 | 75 | func selectRecord() { 76 | select.execute() 77 | } 78 | 79 | func deleteRecord() { 80 | delete.execute() 81 | } 82 | } 83 | /*: 84 | ### Usage: 85 | */ 86 | let database = Database() 87 | let insertCommand = InsertCommand(database: database) 88 | let updateCommand = UpdateCommand(database: database) 89 | let selectCommand = SelectCommand(database: database) 90 | let deleteCommand = DeleteCommand(database: database) 91 | 92 | let developer = Developer(insert: insertCommand, update: updateCommand, select: selectCommand, delete: deleteCommand) 93 | developer.insertRecord() 94 | developer.updateRecord() 95 | developer.selectRecord() 96 | developer.deleteRecord() 97 | -------------------------------------------------------------------------------- /Structural.playground/Pages/Flyweight.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | ## 🍃 Flyweight 13 | The flyweight pattern is used to minimize memory usage or computational expenses by sharing as much as possible with other similar objects. 14 | ### Example 15 | */ 16 | protocol Developer { 17 | func writeCode() 18 | } 19 | 20 | struct SwiftDeveloper: Developer { 21 | func writeCode() { 22 | print("Swift Developer writes Swift code...") 23 | } 24 | } 25 | 26 | struct ObjCDeveloper: Developer { 27 | func writeCode() { 28 | print("ObjC Developer writes Objective-C code...") 29 | } 30 | } 31 | 32 | enum Languages: String { 33 | case Swift 34 | case ObjC 35 | 36 | var description: String { 37 | return self.rawValue 38 | } 39 | } 40 | 41 | struct DeveloperFactory { 42 | private var developers = [String: Developer]() 43 | 44 | mutating func developer(by language: Languages) -> Developer { 45 | if let value = developers[language.description] { 46 | return value 47 | } else { 48 | var value: Developer? = nil 49 | print("Hiring \(language.description) developer ") 50 | switch language { 51 | case .Swift: 52 | value = SwiftDeveloper() 53 | case .ObjC: 54 | value = ObjCDeveloper() 55 | } 56 | developers[language.description] = value 57 | return value! 58 | } 59 | } 60 | } 61 | /*: 62 | ### Usage 63 | */ 64 | var developerFactory = DeveloperFactory() 65 | var developers = [Developer]() 66 | developers.append(developerFactory.developer(by: .Swift)) 67 | developers.append(developerFactory.developer(by: .Swift)) 68 | developers.append(developerFactory.developer(by: .Swift)) 69 | developers.append(developerFactory.developer(by: .ObjC)) 70 | developers.append(developerFactory.developer(by: .ObjC)) 71 | developers.append(developerFactory.developer(by: .ObjC)) 72 | for developer in developers { 73 | developer.writeCode() 74 | } 75 | -------------------------------------------------------------------------------- /source/behavioral/Chain-Of-Responsibility.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🐝 Chain Of Responsibility 3 | -------------------------- 4 | 5 | The chain of responsibility pattern is used to process varied requests, each of which may be dealt with by a different handler. 6 | 7 | ### Example: 8 | */ 9 | protocol Notifier { 10 | var priority: Int { set get } 11 | var nextNotifier: Notifier? { set get } 12 | func write(_ message: String) 13 | } 14 | 15 | extension Notifier { 16 | func notifyManager(message: String, level: Int) { 17 | if level >= priority { 18 | write(message) 19 | } 20 | if let nextNotifie = self.nextNotifier { 21 | nextNotifie.notifyManager(message: message, level: level) 22 | } 23 | } 24 | } 25 | 26 | enum Priority { 27 | case routine 28 | case important 29 | case asSoonAsPossible 30 | } 31 | 32 | struct SimpleReportNotifier: Notifier { 33 | internal var nextNotifier: Notifier? 34 | internal var priority: Int 35 | 36 | func write(_ message: String) { 37 | print("Notifying using simple report: \(message)") 38 | } 39 | } 40 | 41 | struct EmailNotifier: Notifier { 42 | internal var nextNotifier: Notifier? 43 | internal var priority: Int 44 | 45 | func write(_ message: String) { 46 | print("Sending email: \(message)") 47 | } 48 | } 49 | 50 | struct SMSNotifier: Notifier { 51 | internal var nextNotifier: Notifier? 52 | internal var priority: Int 53 | 54 | func write(_ message: String) { 55 | print("Sending sms to manager: \(message)") 56 | } 57 | } 58 | /*: 59 | ### Usage 60 | */ 61 | let smsNotifier = SMSNotifier(nextNotifier: nil, priority: Priority.asSoonAsPossible.hashValue) 62 | let emailNotifier = EmailNotifier(nextNotifier: smsNotifier, priority: Priority.important.hashValue) 63 | let reportNotifier = SimpleReportNotifier(nextNotifier: emailNotifier, priority: Priority.routine.hashValue) 64 | 65 | reportNotifier.notifyManager(message: "Everything is OK", level: Priority.routine.hashValue) 66 | reportNotifier.notifyManager(message: "Something went wrong", level: Priority.important.hashValue) 67 | reportNotifier.notifyManager(message: "Houston, we've had a problem here!", level: Priority.asSoonAsPossible.hashValue) 68 | /*: 69 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Chain-Of-Responsibility) 70 | */ 71 | -------------------------------------------------------------------------------- /source/behavioral/visitor.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🏃 Visitor 3 | ---------- 4 | 5 | The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold. 6 | 7 | ### Example 8 | */ 9 | protocol Developer { 10 | func create(project: ProjectClass) 11 | func create(project: Database) 12 | func create(project: Test) 13 | } 14 | 15 | protocol ProjectElement { 16 | func beWritten(developer: Developer) 17 | } 18 | 19 | struct ProjectClass: ProjectElement { 20 | func beWritten(developer: Developer) { 21 | developer.create(project: self) 22 | } 23 | } 24 | 25 | struct Database: ProjectElement { 26 | func beWritten(developer: Developer) { 27 | developer.create(project: self) 28 | } 29 | } 30 | 31 | struct Test: ProjectElement { 32 | func beWritten(developer: Developer) { 33 | developer.create(project: self) 34 | } 35 | } 36 | 37 | struct Project: ProjectElement { 38 | var projectElements: [ProjectElement] = [ProjectClass(), Database(), Test()] 39 | 40 | func beWritten(developer: Developer) { 41 | for projectElement in projectElements { 42 | projectElement.beWritten(developer: developer) 43 | } 44 | } 45 | } 46 | 47 | struct JuniorDeveloper: Developer { 48 | func create(project: ProjectClass) { 49 | print("Writing poor class...") 50 | } 51 | 52 | func create(project: Database) { 53 | print("Drop database...") 54 | } 55 | 56 | func create(project: Test) { 57 | print("Creating not reliable test...") 58 | } 59 | } 60 | 61 | struct SeniorDeveloper: Developer { 62 | func create(project: ProjectClass) { 63 | print("Rewriting class after junior...") 64 | } 65 | 66 | func create(project: Database) { 67 | print("Fixing database...") 68 | } 69 | 70 | func create(project: Test) { 71 | print("Creating reliable test...") 72 | } 73 | } 74 | /*: 75 | ### Usage 76 | */ 77 | let project = Project() 78 | let junior = JuniorDeveloper() 79 | let senior = SeniorDeveloper() 80 | 81 | print("Junior in Action") 82 | project.beWritten(developer: junior) 83 | 84 | print("") 85 | 86 | print("Senior in Action") 87 | project.beWritten(developer: senior) 88 | /*: 89 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Visitor) 90 | */ 91 | -------------------------------------------------------------------------------- /source/creational/builder.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 👷 Builder 3 | ---------- 4 | 5 | The builder pattern is used to create complex objects with constituent parts that must be created in the same order or using a specific algorithm. 6 | An external class controls the construction algorithm. 7 | 8 | ### Example 9 | */ 10 | enum Cms { 11 | case wordpress 12 | case alifresco 13 | } 14 | 15 | struct Website { 16 | var name: String? 17 | var cms: Cms? 18 | var price: Int? 19 | 20 | func printWebsite(){ 21 | guard let name = name, let cms = cms, let price = price else { 22 | return 23 | } 24 | print("Name \(name), cms \(cms), price \(price)") 25 | } 26 | } 27 | 28 | protocol WebsiteBuilder { 29 | var website: Website? { set get } 30 | func createWebsite() 31 | func buildName() 32 | func buildCms() 33 | func buildPrice() 34 | } 35 | 36 | class VisitCardWebsiteBuilder: WebsiteBuilder { 37 | internal var website: Website? 38 | 39 | internal func createWebsite() { 40 | self.website = Website() 41 | } 42 | 43 | internal func buildName() { 44 | self.website?.name = "Visit Card" 45 | } 46 | 47 | internal func buildCms() { 48 | self.website?.cms = .wordpress 49 | } 50 | 51 | internal func buildPrice() { 52 | self.website?.price = 500 53 | } 54 | } 55 | 56 | class EnterpriseWebsiteBuilder: WebsiteBuilder { 57 | internal var website: Website? 58 | 59 | internal func createWebsite() { 60 | self.website = Website() 61 | } 62 | 63 | internal func buildName() { 64 | self.website?.name = "Enterprise website" 65 | } 66 | 67 | internal func buildCms() { 68 | self.website?.cms = .alifresco 69 | } 70 | 71 | internal func buildPrice() { 72 | self.website?.price = 10000 73 | } 74 | } 75 | 76 | struct Director { 77 | var builder: WebsiteBuilder 78 | 79 | func buildWebsite() -> Website { 80 | builder.createWebsite() 81 | builder.buildName() 82 | builder.buildCms() 83 | builder.buildPrice() 84 | return builder.website! 85 | } 86 | } 87 | /*: 88 | ### Usage 89 | */ 90 | let director = Director(builder: EnterpriseWebsiteBuilder()) 91 | let website = director.buildWebsite() 92 | website.printWebsite() 93 | /*: 94 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Builder) 95 | */ 96 | -------------------------------------------------------------------------------- /source/behavioral/observer.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 👓 Observer 3 | ----------- 4 | 5 | The observer pattern is used to allow an object to publish changes to its state. 6 | Other objects subscribe to be immediately notified of any changes. 7 | 8 | ### Example 9 | */ 10 | protocol Observer { 11 | var name: String { get } 12 | 13 | func handleEvent(vacancies: [String]) 14 | } 15 | 16 | protocol Observed { 17 | mutating func addObserver(observer: Observer) 18 | mutating func removeObserver(observer: Observer) 19 | func notifyObservers() 20 | } 21 | 22 | struct Subscriber: Observer { 23 | var name: String 24 | 25 | func handleEvent(vacancies: [String]) { 26 | print("Dear \(name). We have some changes in vacancies:\n\(vacancies)\n") 27 | } 28 | } 29 | 30 | struct HeadHunter: Observed { 31 | var vacancies = [String]() 32 | var subscribers = [Observer]() 33 | 34 | mutating func addVacancy(vacancy: String) { 35 | vacancies.append(vacancy) 36 | notifyObservers() 37 | } 38 | 39 | mutating func removeVacancy(vacancy: String) { 40 | if let index = vacancies.index(of: vacancy) { 41 | vacancies.remove(at: index) 42 | notifyObservers() 43 | } 44 | } 45 | 46 | mutating func addObserver(observer: Observer) { 47 | subscribers.append(observer) 48 | } 49 | 50 | mutating func removeObserver(observer: Observer) { 51 | for index in 1...subscribers.count - 1 { 52 | let subscriber = subscribers[index] 53 | if subscriber.name == observer.name { 54 | subscribers.remove(at: index) 55 | break 56 | } 57 | } 58 | } 59 | 60 | func notifyObservers() { 61 | for subscriber in subscribers { 62 | subscriber.handleEvent(vacancies: vacancies) 63 | } 64 | } 65 | } 66 | /*: 67 | ### Usage 68 | */ 69 | var hh = HeadHunter() 70 | hh.addVacancy(vacancy: "Swift Developer") 71 | hh.addVacancy(vacancy: "ObjC Developer") 72 | 73 | let zsergey = Subscriber(name: "Sergey Zapuhlyak") 74 | let azimin = Subscriber(name: "Alex Zimin") 75 | 76 | hh.addObserver(observer: zsergey) 77 | hh.addObserver(observer: azimin) 78 | 79 | hh.addVacancy(vacancy: "C++ Developer") 80 | 81 | hh.removeObserver(observer: azimin) 82 | hh.removeVacancy(vacancy: "ObjC Developer") 83 | /*: 84 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Observer) 85 | */ 86 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Interpreter.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🎶 Interpreter 13 | -------------- 14 | 15 | The interpreter pattern is used to evaluate sentences in a language. 16 | 17 | ### Example 18 | */ 19 | protocol Expression { 20 | func interpret(_ context: String) -> Bool 21 | } 22 | 23 | struct AndExpression: Expression { 24 | var expression1: Expression 25 | var expression2: Expression 26 | 27 | func interpret(_ context: String) -> Bool { 28 | return expression1.interpret(context) && expression2.interpret(context) 29 | } 30 | } 31 | 32 | struct OrExpression: Expression { 33 | var expression1: Expression 34 | var expression2: Expression 35 | 36 | func interpret(_ context: String) -> Bool { 37 | return expression1.interpret(context) || expression2.interpret(context) 38 | } 39 | } 40 | 41 | struct TerminalExpression: Expression { 42 | var data: String 43 | 44 | func interpret(_ context: String) -> Bool { 45 | return context.contains(data) 46 | } 47 | } 48 | /*: 49 | ### Usage 50 | */ 51 | struct Interpreter { 52 | static func getAppleExpression() -> Expression { 53 | let swift = TerminalExpression(data: "Swift") 54 | let objC = TerminalExpression(data: "Objective-C") 55 | return OrExpression(expression1: objC, expression2: swift) 56 | } 57 | 58 | static func getJavaEEExpression() -> Expression { 59 | let java = TerminalExpression(data: "Java") 60 | let spring = TerminalExpression(data: "Spring") 61 | return AndExpression(expression1: java, expression2: spring) 62 | } 63 | } 64 | 65 | let appleExpression = Interpreter.getAppleExpression() 66 | let javaExpression = Interpreter.getJavaEEExpression() 67 | print("Is Developer an Apple Developer \(appleExpression.interpret("Swift"))") 68 | print("Does developer knows Java EE \(javaExpression.interpret("Java Spring"))") 69 | /*: 70 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Interpreter) 71 | */ 72 | -------------------------------------------------------------------------------- /source/behavioral/mediator.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 💐 Mediator 3 | ----------- 4 | 5 | The mediator pattern is used to reduce coupling between classes that communicate with each other. Instead of classes communicating directly, and thus requiring knowledge of their implementation, the classes send messages via a mediator object. 6 | 7 | ### Example 8 | */ 9 | protocol Chat { 10 | func sendMessage(_ message: String, from user: User) 11 | } 12 | 13 | protocol User { 14 | var ID: Int { set get } 15 | var name: String { set get } 16 | var chat: Chat { set get } 17 | func sendMessage(_ message: String) 18 | func getMessage(_ message: String) 19 | } 20 | 21 | struct Admin: User { 22 | internal var ID: Int 23 | internal var name: String 24 | internal var chat: Chat 25 | 26 | func sendMessage(_ message: String) { 27 | chat.sendMessage(message, from: self) 28 | } 29 | 30 | func getMessage(_ message: String) { 31 | print("\(name) received message: \(message)") 32 | } 33 | } 34 | 35 | struct Client: User { 36 | internal var ID: Int 37 | internal var name: String 38 | internal var chat: Chat 39 | 40 | func sendMessage(_ message: String) { 41 | chat.sendMessage(message, from: self) 42 | } 43 | 44 | func getMessage(_ message: String) { 45 | print("\(name) received message: \(message)") 46 | } 47 | } 48 | 49 | class Telegram: Chat { 50 | var admin: Admin? 51 | var clients: [Client]? 52 | 53 | func addClient(client: Client) { 54 | if clients == nil { 55 | clients = [Client]() 56 | } 57 | clients?.append(client) 58 | } 59 | 60 | func sendMessage(_ message: String, from user: User) { 61 | if let clients = clients { 62 | for client in clients { 63 | if client.ID != user.ID { 64 | client.getMessage(message) 65 | } 66 | } 67 | } 68 | 69 | admin?.getMessage(message) 70 | } 71 | } 72 | /*: 73 | ### Usage 74 | */ 75 | var telegram = Telegram() 76 | let admin = Admin(ID: 1, name: "Pavel Durov", chat: telegram) 77 | let zsergey = Client(ID: 2, name: "Sergey Zapuhlyak", chat: telegram) 78 | let azimin = Client(ID: 3, name: "Alex Zimin", chat: telegram) 79 | telegram.admin = admin 80 | telegram.addClient(client: zsergey) 81 | telegram.addClient(client: azimin) 82 | 83 | zsergey.sendMessage("Hello, I am Sergey Zapuhlyak") 84 | admin.sendMessage("I am Administrator!") 85 | /*: 86 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Mediator) 87 | */ 88 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Chain-Of-Responsibility.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🐝 Chain Of Responsibility 13 | -------------------------- 14 | 15 | The chain of responsibility pattern is used to process varied requests, each of which may be dealt with by a different handler. 16 | 17 | ### Example: 18 | */ 19 | protocol Notifier { 20 | var priority: Int { set get } 21 | var nextNotifier: Notifier? { set get } 22 | func write(_ message: String) 23 | } 24 | 25 | extension Notifier { 26 | func notifyManager(message: String, level: Int) { 27 | if level >= priority { 28 | write(message) 29 | } 30 | if let nextNotifie = self.nextNotifier { 31 | nextNotifie.notifyManager(message: message, level: level) 32 | } 33 | } 34 | } 35 | 36 | enum Priority { 37 | case routine 38 | case important 39 | case asSoonAsPossible 40 | } 41 | 42 | struct SimpleReportNotifier: Notifier { 43 | internal var nextNotifier: Notifier? 44 | internal var priority: Int 45 | 46 | func write(_ message: String) { 47 | print("Notifying using simple report: \(message)") 48 | } 49 | } 50 | 51 | struct EmailNotifier: Notifier { 52 | internal var nextNotifier: Notifier? 53 | internal var priority: Int 54 | 55 | func write(_ message: String) { 56 | print("Sending email: \(message)") 57 | } 58 | } 59 | 60 | struct SMSNotifier: Notifier { 61 | internal var nextNotifier: Notifier? 62 | internal var priority: Int 63 | 64 | func write(_ message: String) { 65 | print("Sending sms to manager: \(message)") 66 | } 67 | } 68 | /*: 69 | ### Usage 70 | */ 71 | let smsNotifier = SMSNotifier(nextNotifier: nil, priority: Priority.asSoonAsPossible.hashValue) 72 | let emailNotifier = EmailNotifier(nextNotifier: smsNotifier, priority: Priority.important.hashValue) 73 | let reportNotifier = SimpleReportNotifier(nextNotifier: emailNotifier, priority: Priority.routine.hashValue) 74 | 75 | reportNotifier.notifyManager(message: "Everything is OK", level: Priority.routine.hashValue) 76 | reportNotifier.notifyManager(message: "Something went wrong", level: Priority.important.hashValue) 77 | reportNotifier.notifyManager(message: "Houston, we've had a problem here!", level: Priority.asSoonAsPossible.hashValue) 78 | /*: 79 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Chain-Of-Responsibility) 80 | */ 81 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Command.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 👫 Command 13 | ---------- 14 | 15 | The command pattern is used to express a request, including the call to be made and all of its required parameters, in a command object. The command may then be executed immediately or held for later use. 16 | 17 | ### Example: 18 | */ 19 | struct Database { 20 | func insert() { 21 | print("Inserting record...") 22 | } 23 | 24 | func update() { 25 | print("Updating record...") 26 | } 27 | 28 | func select() { 29 | print("Reading record...") 30 | } 31 | 32 | func delete() { 33 | print("Deleting record...") 34 | } 35 | } 36 | 37 | protocol Command { 38 | var database: Database { set get } 39 | func execute() 40 | } 41 | 42 | struct InsertCommand: Command { 43 | internal var database: Database 44 | 45 | func execute() { 46 | database.insert() 47 | } 48 | } 49 | 50 | struct UpdateCommand: Command { 51 | internal var database: Database 52 | 53 | func execute() { 54 | database.update() 55 | } 56 | } 57 | 58 | struct SelectCommand: Command { 59 | internal var database: Database 60 | 61 | func execute() { 62 | database.select() 63 | } 64 | } 65 | 66 | struct DeleteCommand: Command { 67 | internal var database: Database 68 | 69 | func execute() { 70 | database.delete() 71 | } 72 | } 73 | 74 | struct Developer { 75 | var insert, update, select, delete: Command 76 | 77 | func insertRecord() { 78 | insert.execute() 79 | } 80 | 81 | func updateRecord() { 82 | update.execute() 83 | } 84 | 85 | func selectRecord() { 86 | select.execute() 87 | } 88 | 89 | func deleteRecord() { 90 | delete.execute() 91 | } 92 | } 93 | /*: 94 | ### Usage: 95 | */ 96 | let database = Database() 97 | let insertCommand = InsertCommand(database: database) 98 | let updateCommand = UpdateCommand(database: database) 99 | let selectCommand = SelectCommand(database: database) 100 | let deleteCommand = DeleteCommand(database: database) 101 | 102 | let developer = Developer(insert: insertCommand, update: updateCommand, select: selectCommand, delete: deleteCommand) 103 | developer.insertRecord() 104 | developer.updateRecord() 105 | developer.selectRecord() 106 | developer.deleteRecord() 107 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Observer.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 👓 Observer 13 | ----------- 14 | 15 | The observer pattern is used to allow an object to publish changes to its state. 16 | Other objects subscribe to be immediately notified of any changes. 17 | 18 | ### Example 19 | */ 20 | protocol Observer { 21 | var name: String { get } 22 | 23 | func handleEvent(vacancies: [String]) 24 | } 25 | 26 | protocol Observed { 27 | mutating func addObserver(observer: Observer) 28 | mutating func removeObserver(observer: Observer) 29 | func notifyObservers() 30 | } 31 | 32 | struct Subscriber: Observer { 33 | var name: String 34 | 35 | func handleEvent(vacancies: [String]) { 36 | print("Dear \(name). We have some changes in vacancies:\n\(vacancies)\n") 37 | } 38 | } 39 | 40 | struct HeadHunter: Observed { 41 | var vacancies = [String]() 42 | var subscribers = [Observer]() 43 | 44 | mutating func addVacancy(vacancy: String) { 45 | vacancies.append(vacancy) 46 | notifyObservers() 47 | } 48 | 49 | mutating func removeVacancy(vacancy: String) { 50 | if let index = vacancies.index(of: vacancy) { 51 | vacancies.remove(at: index) 52 | notifyObservers() 53 | } 54 | } 55 | 56 | mutating func addObserver(observer: Observer) { 57 | subscribers.append(observer) 58 | } 59 | 60 | mutating func removeObserver(observer: Observer) { 61 | for index in 1...subscribers.count - 1 { 62 | let subscriber = subscribers[index] 63 | if subscriber.name == observer.name { 64 | subscribers.remove(at: index) 65 | break 66 | } 67 | } 68 | } 69 | 70 | func notifyObservers() { 71 | for subscriber in subscribers { 72 | subscriber.handleEvent(vacancies: vacancies) 73 | } 74 | } 75 | } 76 | /*: 77 | ### Usage 78 | */ 79 | var hh = HeadHunter() 80 | hh.addVacancy(vacancy: "Swift Developer") 81 | hh.addVacancy(vacancy: "ObjC Developer") 82 | 83 | let zsergey = Subscriber(name: "Sergey Zapuhlyak") 84 | let azimin = Subscriber(name: "Alex Zimin") 85 | 86 | hh.addObserver(observer: zsergey) 87 | hh.addObserver(observer: azimin) 88 | 89 | hh.addVacancy(vacancy: "C++ Developer") 90 | 91 | hh.removeObserver(observer: azimin) 92 | hh.removeVacancy(vacancy: "ObjC Developer") 93 | /*: 94 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Observer) 95 | */ 96 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Visitor.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🏃 Visitor 13 | ---------- 14 | 15 | The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold. 16 | 17 | ### Example 18 | */ 19 | protocol Developer { 20 | func create(project: ProjectClass) 21 | func create(project: Database) 22 | func create(project: Test) 23 | } 24 | 25 | protocol ProjectElement { 26 | func beWritten(developer: Developer) 27 | } 28 | 29 | struct ProjectClass: ProjectElement { 30 | func beWritten(developer: Developer) { 31 | developer.create(project: self) 32 | } 33 | } 34 | 35 | struct Database: ProjectElement { 36 | func beWritten(developer: Developer) { 37 | developer.create(project: self) 38 | } 39 | } 40 | 41 | struct Test: ProjectElement { 42 | func beWritten(developer: Developer) { 43 | developer.create(project: self) 44 | } 45 | } 46 | 47 | struct Project: ProjectElement { 48 | var projectElements: [ProjectElement] = [ProjectClass(), Database(), Test()] 49 | 50 | func beWritten(developer: Developer) { 51 | for projectElement in projectElements { 52 | projectElement.beWritten(developer: developer) 53 | } 54 | } 55 | } 56 | 57 | struct JuniorDeveloper: Developer { 58 | func create(project: ProjectClass) { 59 | print("Writing poor class...") 60 | } 61 | 62 | func create(project: Database) { 63 | print("Drop database...") 64 | } 65 | 66 | func create(project: Test) { 67 | print("Creating not reliable test...") 68 | } 69 | } 70 | 71 | struct SeniorDeveloper: Developer { 72 | func create(project: ProjectClass) { 73 | print("Rewriting class after junior...") 74 | } 75 | 76 | func create(project: Database) { 77 | print("Fixing database...") 78 | } 79 | 80 | func create(project: Test) { 81 | print("Creating reliable test...") 82 | } 83 | } 84 | /*: 85 | ### Usage 86 | */ 87 | let project = Project() 88 | let junior = JuniorDeveloper() 89 | let senior = SeniorDeveloper() 90 | 91 | print("Junior in Action") 92 | project.beWritten(developer: junior) 93 | 94 | print("") 95 | 96 | print("Senior in Action") 97 | project.beWritten(developer: senior) 98 | /*: 99 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Visitor) 100 | */ 101 | -------------------------------------------------------------------------------- /Behavioral.playground/Pages/Mediator.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 💐 Mediator 13 | ----------- 14 | 15 | The mediator pattern is used to reduce coupling between classes that communicate with each other. Instead of classes communicating directly, and thus requiring knowledge of their implementation, the classes send messages via a mediator object. 16 | 17 | ### Example 18 | */ 19 | protocol Chat { 20 | func sendMessage(_ message: String, from user: User) 21 | } 22 | 23 | protocol User { 24 | var ID: Int { set get } 25 | var name: String { set get } 26 | var chat: Chat { set get } 27 | func sendMessage(_ message: String) 28 | func getMessage(_ message: String) 29 | } 30 | 31 | struct Admin: User { 32 | internal var ID: Int 33 | internal var name: String 34 | internal var chat: Chat 35 | 36 | func sendMessage(_ message: String) { 37 | chat.sendMessage(message, from: self) 38 | } 39 | 40 | func getMessage(_ message: String) { 41 | print("\(name) received message: \(message)") 42 | } 43 | } 44 | 45 | struct Client: User { 46 | internal var ID: Int 47 | internal var name: String 48 | internal var chat: Chat 49 | 50 | func sendMessage(_ message: String) { 51 | chat.sendMessage(message, from: self) 52 | } 53 | 54 | func getMessage(_ message: String) { 55 | print("\(name) received message: \(message)") 56 | } 57 | } 58 | 59 | class Telegram: Chat { 60 | var admin: Admin? 61 | var clients: [Client]? 62 | 63 | func addClient(client: Client) { 64 | if clients == nil { 65 | clients = [Client]() 66 | } 67 | clients?.append(client) 68 | } 69 | 70 | func sendMessage(_ message: String, from user: User) { 71 | if let clients = clients { 72 | for client in clients { 73 | if client.ID != user.ID { 74 | client.getMessage(message) 75 | } 76 | } 77 | } 78 | 79 | admin?.getMessage(message) 80 | } 81 | } 82 | /*: 83 | ### Usage 84 | */ 85 | var telegram = Telegram() 86 | let admin = Admin(ID: 1, name: "Pavel Durov", chat: telegram) 87 | let zsergey = Client(ID: 2, name: "Sergey Zapuhlyak", chat: telegram) 88 | let azimin = Client(ID: 3, name: "Alex Zimin", chat: telegram) 89 | telegram.admin = admin 90 | telegram.addClient(client: zsergey) 91 | telegram.addClient(client: azimin) 92 | 93 | zsergey.sendMessage("Hello, I am Sergey Zapuhlyak") 94 | admin.sendMessage("I am Administrator!") 95 | /*: 96 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Mediator) 97 | */ 98 | -------------------------------------------------------------------------------- /Creational.playground/Pages/Builder.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 👷 Builder 13 | ---------- 14 | 15 | The builder pattern is used to create complex objects with constituent parts that must be created in the same order or using a specific algorithm. 16 | An external class controls the construction algorithm. 17 | 18 | ### Example 19 | */ 20 | enum Cms { 21 | case wordpress 22 | case alifresco 23 | } 24 | 25 | struct Website { 26 | var name: String? 27 | var cms: Cms? 28 | var price: Int? 29 | 30 | func printWebsite(){ 31 | guard let name = name, let cms = cms, let price = price else { 32 | return 33 | } 34 | print("Name \(name), cms \(cms), price \(price)") 35 | } 36 | } 37 | 38 | protocol WebsiteBuilder { 39 | var website: Website? { set get } 40 | func createWebsite() 41 | func buildName() 42 | func buildCms() 43 | func buildPrice() 44 | } 45 | 46 | class VisitCardWebsiteBuilder: WebsiteBuilder { 47 | internal var website: Website? 48 | 49 | internal func createWebsite() { 50 | self.website = Website() 51 | } 52 | 53 | internal func buildName() { 54 | self.website?.name = "Visit Card" 55 | } 56 | 57 | internal func buildCms() { 58 | self.website?.cms = .wordpress 59 | } 60 | 61 | internal func buildPrice() { 62 | self.website?.price = 500 63 | } 64 | } 65 | 66 | class EnterpriseWebsiteBuilder: WebsiteBuilder { 67 | internal var website: Website? 68 | 69 | internal func createWebsite() { 70 | self.website = Website() 71 | } 72 | 73 | internal func buildName() { 74 | self.website?.name = "Enterprise website" 75 | } 76 | 77 | internal func buildCms() { 78 | self.website?.cms = .alifresco 79 | } 80 | 81 | internal func buildPrice() { 82 | self.website?.price = 10000 83 | } 84 | } 85 | 86 | struct Director { 87 | var builder: WebsiteBuilder 88 | 89 | func buildWebsite() -> Website { 90 | builder.createWebsite() 91 | builder.buildName() 92 | builder.buildCms() 93 | builder.buildPrice() 94 | return builder.website! 95 | } 96 | } 97 | /*: 98 | ### Usage 99 | */ 100 | let director = Director(builder: EnterpriseWebsiteBuilder()) 101 | let website = director.buildWebsite() 102 | website.printWebsite() 103 | /*: 104 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Builder) 105 | */ 106 | -------------------------------------------------------------------------------- /source/creational/Abstract-Factory.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | 🌰 Abstract Factory 3 | ------------------- 4 | 5 | The abstract factory pattern is used to provide a client with a set of related or dependant objects. 6 | The "family" of objects created by the factory are determined at run-time. 7 | 8 | ### Example 9 | */ 10 | protocol Developer { 11 | func writeCode() 12 | } 13 | 14 | protocol Tester { 15 | func testCode() 16 | } 17 | 18 | protocol ProjectManager { 19 | func manageProject() 20 | } 21 | 22 | protocol ProjectTeamFactory { 23 | var developer: Developer { get } 24 | var tester: Tester { get } 25 | var projectManager: ProjectManager { get } 26 | } 27 | 28 | // Team of Bank. 29 | struct SwiftDeveloper: Developer { 30 | func writeCode() { 31 | print("Swift developer writes Swift code...") 32 | } 33 | } 34 | 35 | struct QATester: Tester { 36 | func testCode() { 37 | print("QA tester tests banking code...") 38 | } 39 | } 40 | 41 | struct BankingPM: ProjectManager { 42 | func manageProject() { 43 | print("BankingPM manages banking project...") 44 | } 45 | } 46 | 47 | struct BankingTeamFactory: ProjectTeamFactory { 48 | var developer: Developer { 49 | return SwiftDeveloper() 50 | } 51 | var tester: Tester { 52 | return QATester() 53 | } 54 | var projectManager: ProjectManager { 55 | return BankingPM() 56 | } 57 | } 58 | 59 | // Team of Website. 60 | struct PhpDeveloper: Developer { 61 | func writeCode() { 62 | print("Php developer writes php code...") 63 | } 64 | } 65 | 66 | struct ManualTester: Tester { 67 | func testCode() { 68 | print("Manual tester tests Website...") 69 | } 70 | } 71 | 72 | struct WebsitePM: ProjectManager { 73 | func manageProject() { 74 | print("WebsitePM manages Website project...") 75 | } 76 | } 77 | 78 | struct WebsiteTeamFactory: ProjectTeamFactory { 79 | var developer: Developer { 80 | return PhpDeveloper() 81 | } 82 | var tester: Tester { 83 | return ManualTester() 84 | } 85 | var projectManager: ProjectManager { 86 | return WebsitePM() 87 | } 88 | } 89 | 90 | // Projects. 91 | enum Projects { 92 | case bankBusinessOnline 93 | case auctionSite 94 | 95 | var name: String { 96 | switch self { 97 | case .bankBusinessOnline: 98 | return "Bank business online" 99 | case .auctionSite: 100 | return "Auction site" 101 | } 102 | } 103 | 104 | var factory: ProjectTeamFactory { 105 | switch self { 106 | case .bankBusinessOnline: 107 | return BankingTeamFactory() 108 | case .auctionSite: 109 | return WebsiteTeamFactory() 110 | } 111 | } 112 | 113 | func createProject() { 114 | print("Создание проекта \(name)") 115 | let projectFactory = factory 116 | projectFactory.developer.writeCode() 117 | projectFactory.tester.testCode() 118 | projectFactory.projectManager.manageProject() 119 | } 120 | } 121 | /*: 122 | ### Usage 123 | */ 124 | Projects.bankBusinessOnline.createProject() 125 | Projects.auctionSite.createProject() 126 | -------------------------------------------------------------------------------- /Creational.playground/Pages/Abstract-Factory.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🌰 Abstract Factory 13 | ------------------- 14 | 15 | The abstract factory pattern is used to provide a client with a set of related or dependant objects. 16 | The "family" of objects created by the factory are determined at run-time. 17 | 18 | ### Example 19 | */ 20 | protocol Developer { 21 | func writeCode() 22 | } 23 | 24 | protocol Tester { 25 | func testCode() 26 | } 27 | 28 | protocol ProjectManager { 29 | func manageProject() 30 | } 31 | 32 | protocol ProjectTeamFactory { 33 | var developer: Developer { get } 34 | var tester: Tester { get } 35 | var projectManager: ProjectManager { get } 36 | } 37 | 38 | // Team of Bank. 39 | struct SwiftDeveloper: Developer { 40 | func writeCode() { 41 | print("Swift developer writes Swift code...") 42 | } 43 | } 44 | 45 | struct QATester: Tester { 46 | func testCode() { 47 | print("QA tester tests banking code...") 48 | } 49 | } 50 | 51 | struct BankingPM: ProjectManager { 52 | func manageProject() { 53 | print("BankingPM manages banking project...") 54 | } 55 | } 56 | 57 | struct BankingTeamFactory: ProjectTeamFactory { 58 | var developer: Developer { 59 | return SwiftDeveloper() 60 | } 61 | var tester: Tester { 62 | return QATester() 63 | } 64 | var projectManager: ProjectManager { 65 | return BankingPM() 66 | } 67 | } 68 | 69 | // Team of Website. 70 | struct PhpDeveloper: Developer { 71 | func writeCode() { 72 | print("Php developer writes php code...") 73 | } 74 | } 75 | 76 | struct ManualTester: Tester { 77 | func testCode() { 78 | print("Manual tester tests Website...") 79 | } 80 | } 81 | 82 | struct WebsitePM: ProjectManager { 83 | func manageProject() { 84 | print("WebsitePM manages Website project...") 85 | } 86 | } 87 | 88 | struct WebsiteTeamFactory: ProjectTeamFactory { 89 | var developer: Developer { 90 | return PhpDeveloper() 91 | } 92 | var tester: Tester { 93 | return ManualTester() 94 | } 95 | var projectManager: ProjectManager { 96 | return WebsitePM() 97 | } 98 | } 99 | 100 | // Projects. 101 | enum Projects { 102 | case bankBusinessOnline 103 | case auctionSite 104 | 105 | var name: String { 106 | switch self { 107 | case .bankBusinessOnline: 108 | return "Bank business online" 109 | case .auctionSite: 110 | return "Auction site" 111 | } 112 | } 113 | 114 | var factory: ProjectTeamFactory { 115 | switch self { 116 | case .bankBusinessOnline: 117 | return BankingTeamFactory() 118 | case .auctionSite: 119 | return WebsiteTeamFactory() 120 | } 121 | } 122 | 123 | func createProject() { 124 | print("Создание проекта \(name)") 125 | let projectFactory = factory 126 | projectFactory.developer.writeCode() 127 | projectFactory.tester.testCode() 128 | projectFactory.projectManager.manageProject() 129 | } 130 | } 131 | /*: 132 | ### Usage 133 | */ 134 | Projects.bankBusinessOnline.createProject() 135 | Projects.auctionSite.createProject() 136 | -------------------------------------------------------------------------------- /Design-Patterns.playground/Pages/Creational.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Creational 3 | ========== 4 | 5 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🌰 Abstract Factory 13 | ------------------- 14 | 15 | The abstract factory pattern is used to provide a client with a set of related or dependant objects. 16 | The "family" of objects created by the factory are determined at run-time. 17 | 18 | ### Example 19 | */ 20 | protocol Developer { 21 | func writeCode() 22 | } 23 | 24 | protocol Tester { 25 | func testCode() 26 | } 27 | 28 | protocol ProjectManager { 29 | func manageProject() 30 | } 31 | 32 | protocol ProjectTeamFactory { 33 | var developer: Developer { get } 34 | var tester: Tester { get } 35 | var projectManager: ProjectManager { get } 36 | } 37 | 38 | // Team of Bank. 39 | struct SwiftDeveloper: Developer { 40 | func writeCode() { 41 | print("Swift developer writes Swift code...") 42 | } 43 | } 44 | 45 | struct QATester: Tester { 46 | func testCode() { 47 | print("QA tester tests banking code...") 48 | } 49 | } 50 | 51 | struct BankingPM: ProjectManager { 52 | func manageProject() { 53 | print("BankingPM manages banking project...") 54 | } 55 | } 56 | 57 | struct BankingTeamFactory: ProjectTeamFactory { 58 | var developer: Developer { 59 | return SwiftDeveloper() 60 | } 61 | var tester: Tester { 62 | return QATester() 63 | } 64 | var projectManager: ProjectManager { 65 | return BankingPM() 66 | } 67 | } 68 | 69 | // Team of Website. 70 | struct PhpDeveloper: Developer { 71 | func writeCode() { 72 | print("Php developer writes php code...") 73 | } 74 | } 75 | 76 | struct ManualTester: Tester { 77 | func testCode() { 78 | print("Manual tester tests Website...") 79 | } 80 | } 81 | 82 | struct WebsitePM: ProjectManager { 83 | func manageProject() { 84 | print("WebsitePM manages Website project...") 85 | } 86 | } 87 | 88 | struct WebsiteTeamFactory: ProjectTeamFactory { 89 | var developer: Developer { 90 | return PhpDeveloper() 91 | } 92 | var tester: Tester { 93 | return ManualTester() 94 | } 95 | var projectManager: ProjectManager { 96 | return WebsitePM() 97 | } 98 | } 99 | 100 | // Projects. 101 | enum Projects { 102 | case bankBusinessOnline 103 | case auctionSite 104 | 105 | var name: String { 106 | switch self { 107 | case .bankBusinessOnline: 108 | return "Bank business online" 109 | case .auctionSite: 110 | return "Auction site" 111 | } 112 | } 113 | 114 | var factory: ProjectTeamFactory { 115 | switch self { 116 | case .bankBusinessOnline: 117 | return BankingTeamFactory() 118 | case .auctionSite: 119 | return WebsiteTeamFactory() 120 | } 121 | } 122 | 123 | func createProject() { 124 | print("Создание проекта \(name)") 125 | let projectFactory = factory 126 | projectFactory.developer.writeCode() 127 | projectFactory.tester.testCode() 128 | projectFactory.projectManager.manageProject() 129 | } 130 | } 131 | /*: 132 | ### Usage 133 | */ 134 | Projects.bankBusinessOnline.createProject() 135 | Projects.auctionSite.createProject() 136 | /*: 137 | 👷 Builder 138 | ---------- 139 | 140 | The builder pattern is used to create complex objects with constituent parts that must be created in the same order or using a specific algorithm. 141 | An external class controls the construction algorithm. 142 | 143 | ### Example 144 | */ 145 | enum Cms { 146 | case wordpress 147 | case alifresco 148 | } 149 | 150 | struct Website { 151 | var name: String? 152 | var cms: Cms? 153 | var price: Int? 154 | 155 | func printWebsite(){ 156 | guard let name = name, let cms = cms, let price = price else { 157 | return 158 | } 159 | print("Name \(name), cms \(cms), price \(price)") 160 | } 161 | } 162 | 163 | protocol WebsiteBuilder { 164 | var website: Website? { set get } 165 | func createWebsite() 166 | func buildName() 167 | func buildCms() 168 | func buildPrice() 169 | } 170 | 171 | class VisitCardWebsiteBuilder: WebsiteBuilder { 172 | internal var website: Website? 173 | 174 | internal func createWebsite() { 175 | self.website = Website() 176 | } 177 | 178 | internal func buildName() { 179 | self.website?.name = "Visit Card" 180 | } 181 | 182 | internal func buildCms() { 183 | self.website?.cms = .wordpress 184 | } 185 | 186 | internal func buildPrice() { 187 | self.website?.price = 500 188 | } 189 | } 190 | 191 | class EnterpriseWebsiteBuilder: WebsiteBuilder { 192 | internal var website: Website? 193 | 194 | internal func createWebsite() { 195 | self.website = Website() 196 | } 197 | 198 | internal func buildName() { 199 | self.website?.name = "Enterprise website" 200 | } 201 | 202 | internal func buildCms() { 203 | self.website?.cms = .alifresco 204 | } 205 | 206 | internal func buildPrice() { 207 | self.website?.price = 10000 208 | } 209 | } 210 | 211 | struct Director { 212 | var builder: WebsiteBuilder 213 | 214 | func buildWebsite() -> Website { 215 | builder.createWebsite() 216 | builder.buildName() 217 | builder.buildCms() 218 | builder.buildPrice() 219 | return builder.website! 220 | } 221 | } 222 | /*: 223 | ### Usage 224 | */ 225 | let director = Director(builder: EnterpriseWebsiteBuilder()) 226 | let website = director.buildWebsite() 227 | website.printWebsite() 228 | /*: 229 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Builder) 230 | */ 231 | /*: 232 | 🏭 Factory Method 233 | ----------------- 234 | 235 | The factory pattern is used to replace class constructors, abstracting the process of object generation so that the type of the object instantiated can be determined at run-time. 236 | 237 | ### Example 238 | */ 239 | protocol Developer { 240 | func writeCode() 241 | } 242 | 243 | struct ObjCDeveloper: Developer { 244 | func writeCode() { 245 | print("ObjC developer writes Objective C code...") 246 | } 247 | } 248 | 249 | struct SwiftDeveloper: Developer { 250 | func writeCode() { 251 | print("Swift developer writes Swift code...") 252 | } 253 | } 254 | 255 | protocol DeveloperFactory { 256 | func newDeveloper() -> Developer 257 | } 258 | 259 | struct ObjCDeveloperFactory: DeveloperFactory { 260 | func newDeveloper() -> Developer { 261 | return ObjCDeveloper() 262 | } 263 | } 264 | 265 | struct SwiftDeveloperFactory: DeveloperFactory { 266 | func newDeveloper() -> Developer { 267 | return SwiftDeveloper() 268 | } 269 | } 270 | 271 | enum Languages { 272 | case objC 273 | case swift 274 | 275 | var factory: DeveloperFactory { 276 | switch self { 277 | case .objC: 278 | return ObjCDeveloperFactory() 279 | case .swift: 280 | return SwiftDeveloperFactory() 281 | } 282 | } 283 | } 284 | /*: 285 | ### Usage 286 | */ 287 | let developer = Languages.swift.factory.newDeveloper() 288 | developer.writeCode() 289 | /*: 290 | 🃏 Prototype 291 | ------------ 292 | 293 | The prototype pattern is used to instantiate a new object by copying all of the properties of an existing object, creating an independent clone. 294 | This practise is particularly useful when the construction of a new object is inefficient. 295 | 296 | ### Example 297 | */ 298 | protocol Copyable { 299 | func copy() -> Any 300 | } 301 | 302 | struct Project: Copyable { 303 | var id: Int 304 | var name: String 305 | var source: String 306 | 307 | func copy() -> Any { 308 | let object = Project(id: id, name: name, source: source) 309 | return object 310 | } 311 | } 312 | 313 | struct ProjectFactory { 314 | var project: Project 315 | func cloneProject() -> Project { 316 | return project.copy() as! Project 317 | } 318 | } 319 | /*: 320 | ### Usage 321 | */ 322 | let master = Project(id: 1, name: "Playground.swift", source: "let sourceCode = SourceCode()") 323 | let factory = ProjectFactory(project: master) 324 | let masterClone = factory.cloneProject() 325 | /*: 326 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Prototype) 327 | */ 328 | /*: 329 | 💍 Singleton 330 | ------------ 331 | 332 | The singleton pattern ensures that only one object of a particular class is ever created. 333 | All further references to objects of the singleton class refer to the same underlying instance. 334 | There are very few applications, do not overuse this pattern! 335 | 336 | ### Example: 337 | */ 338 | struct Game { 339 | static let sharedGame = Game() 340 | 341 | private init() { 342 | 343 | } 344 | } 345 | /*: 346 | ### Usage: 347 | */ 348 | let game = Game.sharedGame 349 | -------------------------------------------------------------------------------- /Design-Patterns.playground/Pages/Structural.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Structural 3 | ========== 4 | 5 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🔌 Adapter 13 | ---------- 14 | 15 | The adapter pattern is used to provide a link between two otherwise incompatible types by wrapping the "adaptee" with a class that supports the interface required by the client. 16 | 17 | ### Example 18 | */ 19 | protocol Database { 20 | func insert() 21 | func update() 22 | func select() 23 | func remove() 24 | } 25 | 26 | class SwiftApp { 27 | func saveObject() { 28 | print("Saving Swift Object...") 29 | } 30 | 31 | func updateObject() { 32 | print("Updating Swift Object...") 33 | } 34 | 35 | func loadObject() { 36 | print("Loading Swift Object...") 37 | } 38 | 39 | func deleteObject() { 40 | print("Deleting Swift Object...") 41 | } 42 | } 43 | 44 | class AdapterSwiftAppToDatabase: SwiftApp, Database { 45 | func insert() { 46 | saveObject() 47 | } 48 | 49 | func update() { 50 | updateObject() 51 | } 52 | 53 | func select() { 54 | loadObject() 55 | } 56 | 57 | func remove() { 58 | deleteObject() 59 | } 60 | } 61 | 62 | struct DatabaseManager { 63 | var database: Database 64 | func run() { 65 | database.insert() 66 | database.update() 67 | database.select() 68 | database.remove() 69 | } 70 | } 71 | /*: 72 | ### Usage 73 | */ 74 | let databaseManager = DatabaseManager(database: AdapterSwiftAppToDatabase()) 75 | databaseManager.run() 76 | /*: 77 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Adapter) 78 | */ 79 | /*: 80 | 🌉 Bridge 81 | ---------- 82 | 83 | The bridge pattern is used to separate the abstract elements of a class from the implementation details, providing the means to replace the implementation details without modifying the abstraction. 84 | 85 | ### Example 86 | */ 87 | protocol Developer { 88 | func writeCode() 89 | } 90 | 91 | protocol Program { 92 | var developer: Developer { get set } 93 | func develop() 94 | } 95 | 96 | struct SwiftDeveloper: Developer { 97 | func writeCode() { 98 | print("Swift Developer writes Swift code...") 99 | } 100 | } 101 | 102 | struct ObjCDeveloper: Developer { 103 | func writeCode() { 104 | print("ObjC Developer writes Objective-C code...") 105 | } 106 | } 107 | 108 | struct BankSystem: Program { 109 | var developer: Developer 110 | 111 | func develop() { 112 | print("Bank System development in progress...") 113 | developer.writeCode() 114 | } 115 | } 116 | 117 | struct StockExchange: Program { 118 | var developer: Developer 119 | 120 | func develop() { 121 | print("Stock Exchange development in progress...") 122 | developer.writeCode() 123 | } 124 | } 125 | /*: 126 | ### Usage 127 | */ 128 | let programs: [Program] = [BankSystem(developer: ObjCDeveloper()), 129 | StockExchange(developer: SwiftDeveloper())] 130 | for program in programs { 131 | program.develop() 132 | } 133 | /*: 134 | 🌿 Composite 135 | ------------- 136 | 137 | The composite pattern is used to create hierarchical, recursive tree structures of related objects where any element of the structure may be accessed and utilised in a standard manner. 138 | 139 | ### Example 140 | */ 141 | protocol Developer { 142 | func writeCode() 143 | } 144 | 145 | protocol Team { 146 | var developers: [Developer] { set get } 147 | func addDeveloper(developer: Developer) 148 | func createProject() 149 | } 150 | 151 | struct SwiftDeveloper: Developer{ 152 | func writeCode() { 153 | print("Swift Developer writes Swift code...") 154 | } 155 | } 156 | 157 | struct ObjCDeveloper: Developer{ 158 | func writeCode() { 159 | print("ObjC Developer writes Objective-C code...") 160 | } 161 | } 162 | 163 | class BankTeam: Team { 164 | var developers = [Developer]() 165 | 166 | func addDeveloper(developer: Developer) { 167 | developers.append(developer) 168 | } 169 | 170 | func createProject() { 171 | for developer in developers { 172 | developer.writeCode() 173 | } 174 | } 175 | } 176 | /*: 177 | ### Usage: 178 | */ 179 | let team = BankTeam() 180 | team.addDeveloper(developer: ObjCDeveloper()) 181 | team.addDeveloper(developer: ObjCDeveloper()) 182 | team.addDeveloper(developer: ObjCDeveloper()) 183 | team.addDeveloper(developer: ObjCDeveloper()) 184 | team.addDeveloper(developer: SwiftDeveloper()) 185 | team.createProject() 186 | /*: 187 | 🍧 Decorator 188 | ------------ 189 | 190 | The decorator pattern is used to extend or alter the functionality of objects at run- time by wrapping them in an object of a decorator class. 191 | This provides a flexible alternative to using inheritance to modify behaviour. 192 | 193 | ### Example 194 | */ 195 | protocol Developer { 196 | func makeJob() -> String 197 | } 198 | 199 | struct SwiftDeveloper: Developer { 200 | func makeJob() -> String { 201 | return "Write Swift code" 202 | } 203 | } 204 | 205 | class DeveloperDecorator: Developer { 206 | var developer: Developer 207 | func makeJob() -> String { 208 | return developer.makeJob() 209 | } 210 | init(developer: Developer) { 211 | self.developer = developer 212 | } 213 | } 214 | 215 | class SeniorSwiftDeveloper: DeveloperDecorator { 216 | let codeReview = "Make code review" 217 | override func makeJob() -> String { 218 | return super.makeJob() + " & " + codeReview 219 | } 220 | } 221 | 222 | class SwiftTeamLead: DeveloperDecorator { 223 | let sendWeekReport = "Send week report" 224 | override func makeJob() -> String { 225 | return super.makeJob() + " & " + sendWeekReport 226 | } 227 | } 228 | /*: 229 | ### Usage: 230 | */ 231 | let developer = SwiftTeamLead(developer: SeniorSwiftDeveloper(developer: SwiftDeveloper())) 232 | print(developer.makeJob()) 233 | /*: 234 | 🎁 Façade 235 | --------- 236 | 237 | The facade pattern is used to define a simplified interface to a more complex subsystem. 238 | 239 | ### Example 240 | */ 241 | class Job { 242 | func doJob() { 243 | print("Job is progress...") 244 | } 245 | } 246 | 247 | class BugTracker { 248 | var isActiveSprint = false 249 | 250 | func startSprint() { 251 | print("Sprint is active") 252 | isActiveSprint = true 253 | } 254 | 255 | func stopSprint() { 256 | print("Sprint is not active") 257 | isActiveSprint = false 258 | } 259 | } 260 | 261 | class Developer { 262 | func doJobBeforeDeadline(bugTracker: BugTracker) { 263 | if bugTracker.isActiveSprint { 264 | print("Developer is solving problems...") 265 | } else { 266 | print("Developer is reading the news...") 267 | } 268 | } 269 | } 270 | 271 | class Workflow { 272 | let developer = Developer() 273 | let job = Job() 274 | let bugTracker = BugTracker() 275 | func solveProblems() { 276 | job.doJob() 277 | bugTracker.startSprint() 278 | developer.doJobBeforeDeadline(bugTracker: bugTracker) 279 | } 280 | } 281 | /*: 282 | ### Usage 283 | */ 284 | let workflow = Workflow() 285 | workflow.solveProblems() 286 | /*: 287 | ## 🍃 Flyweight 288 | The flyweight pattern is used to minimize memory usage or computational expenses by sharing as much as possible with other similar objects. 289 | ### Example 290 | */ 291 | protocol Developer { 292 | func writeCode() 293 | } 294 | 295 | struct SwiftDeveloper: Developer { 296 | func writeCode() { 297 | print("Swift Developer writes Swift code...") 298 | } 299 | } 300 | 301 | struct ObjCDeveloper: Developer { 302 | func writeCode() { 303 | print("ObjC Developer writes Objective-C code...") 304 | } 305 | } 306 | 307 | enum Languages: String { 308 | case Swift 309 | case ObjC 310 | 311 | var description: String { 312 | return self.rawValue 313 | } 314 | } 315 | 316 | struct DeveloperFactory { 317 | private var developers = [String: Developer]() 318 | 319 | mutating func developer(by language: Languages) -> Developer { 320 | if let value = developers[language.description] { 321 | return value 322 | } else { 323 | var value: Developer? = nil 324 | print("Hiring \(language.description) developer ") 325 | switch language { 326 | case .Swift: 327 | value = SwiftDeveloper() 328 | case .ObjC: 329 | value = ObjCDeveloper() 330 | } 331 | developers[language.description] = value 332 | return value! 333 | } 334 | } 335 | } 336 | /*: 337 | ### Usage 338 | */ 339 | var developerFactory = DeveloperFactory() 340 | var developers = [Developer]() 341 | developers.append(developerFactory.developer(by: .Swift)) 342 | developers.append(developerFactory.developer(by: .Swift)) 343 | developers.append(developerFactory.developer(by: .Swift)) 344 | developers.append(developerFactory.developer(by: .ObjC)) 345 | developers.append(developerFactory.developer(by: .ObjC)) 346 | developers.append(developerFactory.developer(by: .ObjC)) 347 | for developer in developers { 348 | developer.writeCode() 349 | } 350 | /*: 351 | ☔ Proxy 352 | ------------------ 353 | 354 | The proxy pattern is used to provide a surrogate or placeholder object, which references an underlying object. 355 | 356 | ### Example 357 | */ 358 | protocol Project { 359 | func run() 360 | } 361 | 362 | struct RealProject: Project { 363 | var url: String 364 | 365 | func load() { 366 | print("Loading project from url \(url) ...") 367 | } 368 | 369 | init(url: String) { 370 | self.url = url 371 | load() 372 | } 373 | 374 | func run() { 375 | print("Running project \(url) ...") 376 | } 377 | } 378 | 379 | class ProxyProject: Project { 380 | var url: String 381 | var realProject: RealProject? 382 | 383 | func run() { 384 | if realProject == nil { 385 | realProject = RealProject(url: url) 386 | } 387 | realProject!.run() 388 | } 389 | 390 | init(url: String) { 391 | self.url = url 392 | } 393 | } 394 | /*: 395 | ### Usage 396 | */ 397 | var project = ProxyProject(url: "https://github.com/zsergey/realProject") 398 | project.run() 399 | -------------------------------------------------------------------------------- /Design-Patterns.playground/Pages/Behavioral.xcplaygroundpage/Contents.swift: -------------------------------------------------------------------------------- 1 | /*: 2 | Behavioral 3 | ========== 4 | 5 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 6 | > 7 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 8 | */ 9 | import Swift 10 | import Foundation 11 | /*: 12 | 🐝 Chain Of Responsibility 13 | -------------------------- 14 | 15 | The chain of responsibility pattern is used to process varied requests, each of which may be dealt with by a different handler. 16 | 17 | ### Example: 18 | */ 19 | protocol Notifier { 20 | var priority: Int { set get } 21 | var nextNotifier: Notifier? { set get } 22 | func write(_ message: String) 23 | } 24 | 25 | extension Notifier { 26 | func notifyManager(message: String, level: Int) { 27 | if level >= priority { 28 | write(message) 29 | } 30 | if let nextNotifie = self.nextNotifier { 31 | nextNotifie.notifyManager(message: message, level: level) 32 | } 33 | } 34 | } 35 | 36 | enum Priority { 37 | case routine 38 | case important 39 | case asSoonAsPossible 40 | } 41 | 42 | struct SimpleReportNotifier: Notifier { 43 | internal var nextNotifier: Notifier? 44 | internal var priority: Int 45 | 46 | func write(_ message: String) { 47 | print("Notifying using simple report: \(message)") 48 | } 49 | } 50 | 51 | struct EmailNotifier: Notifier { 52 | internal var nextNotifier: Notifier? 53 | internal var priority: Int 54 | 55 | func write(_ message: String) { 56 | print("Sending email: \(message)") 57 | } 58 | } 59 | 60 | struct SMSNotifier: Notifier { 61 | internal var nextNotifier: Notifier? 62 | internal var priority: Int 63 | 64 | func write(_ message: String) { 65 | print("Sending sms to manager: \(message)") 66 | } 67 | } 68 | /*: 69 | ### Usage 70 | */ 71 | let smsNotifier = SMSNotifier(nextNotifier: nil, priority: Priority.asSoonAsPossible.hashValue) 72 | let emailNotifier = EmailNotifier(nextNotifier: smsNotifier, priority: Priority.important.hashValue) 73 | let reportNotifier = SimpleReportNotifier(nextNotifier: emailNotifier, priority: Priority.routine.hashValue) 74 | 75 | reportNotifier.notifyManager(message: "Everything is OK", level: Priority.routine.hashValue) 76 | reportNotifier.notifyManager(message: "Something went wrong", level: Priority.important.hashValue) 77 | reportNotifier.notifyManager(message: "Houston, we've had a problem here!", level: Priority.asSoonAsPossible.hashValue) 78 | /*: 79 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Chain-Of-Responsibility) 80 | */ 81 | /*: 82 | 👫 Command 83 | ---------- 84 | 85 | The command pattern is used to express a request, including the call to be made and all of its required parameters, in a command object. The command may then be executed immediately or held for later use. 86 | 87 | ### Example: 88 | */ 89 | struct Database { 90 | func insert() { 91 | print("Inserting record...") 92 | } 93 | 94 | func update() { 95 | print("Updating record...") 96 | } 97 | 98 | func select() { 99 | print("Reading record...") 100 | } 101 | 102 | func delete() { 103 | print("Deleting record...") 104 | } 105 | } 106 | 107 | protocol Command { 108 | var database: Database { set get } 109 | func execute() 110 | } 111 | 112 | struct InsertCommand: Command { 113 | internal var database: Database 114 | 115 | func execute() { 116 | database.insert() 117 | } 118 | } 119 | 120 | struct UpdateCommand: Command { 121 | internal var database: Database 122 | 123 | func execute() { 124 | database.update() 125 | } 126 | } 127 | 128 | struct SelectCommand: Command { 129 | internal var database: Database 130 | 131 | func execute() { 132 | database.select() 133 | } 134 | } 135 | 136 | struct DeleteCommand: Command { 137 | internal var database: Database 138 | 139 | func execute() { 140 | database.delete() 141 | } 142 | } 143 | 144 | struct Developer { 145 | var insert, update, select, delete: Command 146 | 147 | func insertRecord() { 148 | insert.execute() 149 | } 150 | 151 | func updateRecord() { 152 | update.execute() 153 | } 154 | 155 | func selectRecord() { 156 | select.execute() 157 | } 158 | 159 | func deleteRecord() { 160 | delete.execute() 161 | } 162 | } 163 | /*: 164 | ### Usage: 165 | */ 166 | let database = Database() 167 | let insertCommand = InsertCommand(database: database) 168 | let updateCommand = UpdateCommand(database: database) 169 | let selectCommand = SelectCommand(database: database) 170 | let deleteCommand = DeleteCommand(database: database) 171 | 172 | let developer = Developer(insert: insertCommand, update: updateCommand, select: selectCommand, delete: deleteCommand) 173 | developer.insertRecord() 174 | developer.updateRecord() 175 | developer.selectRecord() 176 | developer.deleteRecord() 177 | /*: 178 | 🎶 Interpreter 179 | -------------- 180 | 181 | The interpreter pattern is used to evaluate sentences in a language. 182 | 183 | ### Example 184 | */ 185 | protocol Expression { 186 | func interpret(_ context: String) -> Bool 187 | } 188 | 189 | struct AndExpression: Expression { 190 | var expression1: Expression 191 | var expression2: Expression 192 | 193 | func interpret(_ context: String) -> Bool { 194 | return expression1.interpret(context) && expression2.interpret(context) 195 | } 196 | } 197 | 198 | struct OrExpression: Expression { 199 | var expression1: Expression 200 | var expression2: Expression 201 | 202 | func interpret(_ context: String) -> Bool { 203 | return expression1.interpret(context) || expression2.interpret(context) 204 | } 205 | } 206 | 207 | struct TerminalExpression: Expression { 208 | var data: String 209 | 210 | func interpret(_ context: String) -> Bool { 211 | return context.contains(data) 212 | } 213 | } 214 | /*: 215 | ### Usage 216 | */ 217 | struct Interpreter { 218 | static func getAppleExpression() -> Expression { 219 | let swift = TerminalExpression(data: "Swift") 220 | let objC = TerminalExpression(data: "Objective-C") 221 | return OrExpression(expression1: objC, expression2: swift) 222 | } 223 | 224 | static func getJavaEEExpression() -> Expression { 225 | let java = TerminalExpression(data: "Java") 226 | let spring = TerminalExpression(data: "Spring") 227 | return AndExpression(expression1: java, expression2: spring) 228 | } 229 | } 230 | 231 | let appleExpression = Interpreter.getAppleExpression() 232 | let javaExpression = Interpreter.getJavaEEExpression() 233 | print("Is Developer an Apple Developer \(appleExpression.interpret("Swift"))") 234 | print("Does developer knows Java EE \(javaExpression.interpret("Java Spring"))") 235 | /*: 236 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Interpreter) 237 | */ 238 | /*: 239 | 🍫 Iterator 240 | ----------- 241 | 242 | The iterator pattern is used to provide a standard interface for traversing a collection of items in an aggregate object without the need to understand its underlying structure. 243 | 244 | ### Example: 245 | */ 246 | protocol Iterator { 247 | func hasNext() -> Bool 248 | mutating func next() -> String 249 | } 250 | 251 | protocol Collection { 252 | func getIterator() -> Iterator 253 | } 254 | 255 | struct SwiftDeveloper: Collection { 256 | var name: String 257 | var skills: [String] 258 | 259 | private struct SkillIterator: Iterator { 260 | var index: Int 261 | var data: [String] 262 | func hasNext() -> Bool { 263 | return index < data.count 264 | } 265 | mutating func next() -> String { 266 | let result = data[index] 267 | index = index + 1 268 | return result 269 | } 270 | } 271 | 272 | func getIterator() -> Iterator { 273 | return SkillIterator(index: 0, data: skills) 274 | } 275 | } 276 | /*: 277 | ### Usage 278 | */ 279 | let skills = ["Swift", "ObjC", "Sketch", "PM"] 280 | let swiftDeveloper = SwiftDeveloper(name: "Sergey Zapuhlyak", skills: skills) 281 | var iterator = swiftDeveloper.getIterator() 282 | print("Developer \(swiftDeveloper.name)") 283 | print("Skills") 284 | while iterator.hasNext() { 285 | print("\(iterator.next())") 286 | } 287 | /*: 288 | 💐 Mediator 289 | ----------- 290 | 291 | The mediator pattern is used to reduce coupling between classes that communicate with each other. Instead of classes communicating directly, and thus requiring knowledge of their implementation, the classes send messages via a mediator object. 292 | 293 | ### Example 294 | */ 295 | protocol Chat { 296 | func sendMessage(_ message: String, from user: User) 297 | } 298 | 299 | protocol User { 300 | var ID: Int { set get } 301 | var name: String { set get } 302 | var chat: Chat { set get } 303 | func sendMessage(_ message: String) 304 | func getMessage(_ message: String) 305 | } 306 | 307 | struct Admin: User { 308 | internal var ID: Int 309 | internal var name: String 310 | internal var chat: Chat 311 | 312 | func sendMessage(_ message: String) { 313 | chat.sendMessage(message, from: self) 314 | } 315 | 316 | func getMessage(_ message: String) { 317 | print("\(name) received message: \(message)") 318 | } 319 | } 320 | 321 | struct Client: User { 322 | internal var ID: Int 323 | internal var name: String 324 | internal var chat: Chat 325 | 326 | func sendMessage(_ message: String) { 327 | chat.sendMessage(message, from: self) 328 | } 329 | 330 | func getMessage(_ message: String) { 331 | print("\(name) received message: \(message)") 332 | } 333 | } 334 | 335 | class Telegram: Chat { 336 | var admin: Admin? 337 | var clients: [Client]? 338 | 339 | func addClient(client: Client) { 340 | if clients == nil { 341 | clients = [Client]() 342 | } 343 | clients?.append(client) 344 | } 345 | 346 | func sendMessage(_ message: String, from user: User) { 347 | if let clients = clients { 348 | for client in clients { 349 | if client.ID != user.ID { 350 | client.getMessage(message) 351 | } 352 | } 353 | } 354 | 355 | admin?.getMessage(message) 356 | } 357 | } 358 | /*: 359 | ### Usage 360 | */ 361 | var telegram = Telegram() 362 | let admin = Admin(ID: 1, name: "Pavel Durov", chat: telegram) 363 | let zsergey = Client(ID: 2, name: "Sergey Zapuhlyak", chat: telegram) 364 | let azimin = Client(ID: 3, name: "Alex Zimin", chat: telegram) 365 | telegram.admin = admin 366 | telegram.addClient(client: zsergey) 367 | telegram.addClient(client: azimin) 368 | 369 | zsergey.sendMessage("Hello, I am Sergey Zapuhlyak") 370 | admin.sendMessage("I am Administrator!") 371 | /*: 372 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Mediator) 373 | */ 374 | /*: 375 | 💾 Memento 376 | ---------- 377 | 378 | The memento pattern is used to capture the current state of an object and store it in such a manner that it can be restored at a later time without breaking the rules of encapsulation. 379 | 380 | ### Example 381 | */ 382 | struct Project { 383 | var version: String 384 | var code: String 385 | 386 | func save() -> Save { 387 | return Save(version: version, code: code) 388 | } 389 | 390 | mutating func load(save: Save) { 391 | version = save.version 392 | code = save.code 393 | } 394 | 395 | func description() -> String { 396 | return "Project version = \(version): \n'\(code)'\n" 397 | } 398 | } 399 | 400 | struct Save { 401 | var version: String 402 | var code: String 403 | } 404 | 405 | struct GithubRepo { 406 | var save: Save 407 | } 408 | /*: 409 | ### Usage 410 | */ 411 | print("Creating new project. Version 1.0") 412 | var project = Project(version: "1.0", code: "let index = 0") 413 | print(project.description()) 414 | 415 | print("Saving current version to github") 416 | let github = GithubRepo(save: project.save()) 417 | 418 | print("Updating project to Version 1.1") 419 | print("Writing poor code...") 420 | print("Set version 1.1") 421 | project.version = "1.1" 422 | project.code = "let index = 0\nindex = 5" 423 | print(project.description()) 424 | 425 | print("Something went wrong") 426 | print("Rolling back to Version 1.0") 427 | 428 | project.load(save: github.save) 429 | print("Project after rollback") 430 | print(project.description()) 431 | /*: 432 | 👓 Observer 433 | ----------- 434 | 435 | The observer pattern is used to allow an object to publish changes to its state. 436 | Other objects subscribe to be immediately notified of any changes. 437 | 438 | ### Example 439 | */ 440 | protocol Observer { 441 | var name: String { get } 442 | 443 | func handleEvent(vacancies: [String]) 444 | } 445 | 446 | protocol Observed { 447 | mutating func addObserver(observer: Observer) 448 | mutating func removeObserver(observer: Observer) 449 | func notifyObservers() 450 | } 451 | 452 | struct Subscriber: Observer { 453 | var name: String 454 | 455 | func handleEvent(vacancies: [String]) { 456 | print("Dear \(name). We have some changes in vacancies:\n\(vacancies)\n") 457 | } 458 | } 459 | 460 | struct HeadHunter: Observed { 461 | var vacancies = [String]() 462 | var subscribers = [Observer]() 463 | 464 | mutating func addVacancy(vacancy: String) { 465 | vacancies.append(vacancy) 466 | notifyObservers() 467 | } 468 | 469 | mutating func removeVacancy(vacancy: String) { 470 | if let index = vacancies.index(of: vacancy) { 471 | vacancies.remove(at: index) 472 | notifyObservers() 473 | } 474 | } 475 | 476 | mutating func addObserver(observer: Observer) { 477 | subscribers.append(observer) 478 | } 479 | 480 | mutating func removeObserver(observer: Observer) { 481 | for index in 1...subscribers.count - 1 { 482 | let subscriber = subscribers[index] 483 | if subscriber.name == observer.name { 484 | subscribers.remove(at: index) 485 | break 486 | } 487 | } 488 | } 489 | 490 | func notifyObservers() { 491 | for subscriber in subscribers { 492 | subscriber.handleEvent(vacancies: vacancies) 493 | } 494 | } 495 | } 496 | /*: 497 | ### Usage 498 | */ 499 | var hh = HeadHunter() 500 | hh.addVacancy(vacancy: "Swift Developer") 501 | hh.addVacancy(vacancy: "ObjC Developer") 502 | 503 | let zsergey = Subscriber(name: "Sergey Zapuhlyak") 504 | let azimin = Subscriber(name: "Alex Zimin") 505 | 506 | hh.addObserver(observer: zsergey) 507 | hh.addObserver(observer: azimin) 508 | 509 | hh.addVacancy(vacancy: "C++ Developer") 510 | 511 | hh.removeObserver(observer: azimin) 512 | hh.removeVacancy(vacancy: "ObjC Developer") 513 | /*: 514 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Observer) 515 | */ 516 | /*: 517 | 🐉 State 518 | --------- 519 | 520 | The state pattern is used to alter the behaviour of an object as its internal state changes. 521 | The pattern allows the class for an object to apparently change at run-time. 522 | 523 | ### Example 524 | */ 525 | protocol Activity { 526 | func justDoIt() 527 | } 528 | 529 | struct Coding: Activity { 530 | func justDoIt() { 531 | print("Writing code...") 532 | } 533 | } 534 | 535 | struct Reading: Activity { 536 | func justDoIt() { 537 | print("Reading book...") 538 | } 539 | } 540 | 541 | struct Sleeping: Activity { 542 | func justDoIt() { 543 | print("Sleeping...") 544 | } 545 | } 546 | 547 | struct Training: Activity { 548 | func justDoIt() { 549 | print("Training...") 550 | } 551 | } 552 | 553 | struct Developer { 554 | var activity: Activity 555 | 556 | mutating func changeActivity() { 557 | if let _ = activity as? Sleeping { 558 | activity = Training() 559 | } else if let _ = activity as? Training { 560 | activity = Coding() 561 | } else if let _ = activity as? Coding { 562 | activity = Reading() 563 | } else if let _ = activity as? Reading { 564 | activity = Sleeping() 565 | } 566 | } 567 | 568 | func justDoIt() { 569 | activity.justDoIt() 570 | } 571 | } 572 | /*: 573 | ### Usage 574 | */ 575 | let activity = Sleeping() 576 | var developer = Developer(activity: activity) 577 | for i in 0..<10 { 578 | developer.justDoIt() 579 | developer.changeActivity() 580 | } 581 | /*: 582 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-State) 583 | */ 584 | /*: 585 | 💡 Strategy 586 | ----------- 587 | 588 | The strategy pattern is used to create an interchangeable family of algorithms from which the required process is chosen at run-time. 589 | 590 | ### Example 591 | */ 592 | protocol Activity { 593 | func justDoIt() 594 | } 595 | 596 | struct Coding: Activity { 597 | func justDoIt() { 598 | print("Writing code...") 599 | } 600 | } 601 | 602 | struct Reading: Activity { 603 | func justDoIt() { 604 | print("Reading book...") 605 | } 606 | } 607 | 608 | struct Sleeping: Activity { 609 | func justDoIt() { 610 | print("Sleeping...") 611 | } 612 | } 613 | 614 | struct Training: Activity { 615 | func justDoIt() { 616 | print("Training...") 617 | } 618 | } 619 | 620 | struct Developer { 621 | var activity: Activity 622 | 623 | func executeActivity() { 624 | activity.justDoIt() 625 | } 626 | } 627 | /*: 628 | ### Usage 629 | */ 630 | var developer = Developer(activity: Sleeping()) 631 | developer.executeActivity() 632 | 633 | developer.activity = Training() 634 | developer.executeActivity() 635 | 636 | developer.activity = Coding() 637 | developer.executeActivity() 638 | 639 | developer.activity = Reading() 640 | developer.executeActivity() 641 | 642 | developer.activity = Sleeping() 643 | developer.executeActivity() 644 | /*: 645 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Strategy) 646 | */ 647 | /*: 648 | 🐾 Template Method 649 | ---------- 650 | 651 | The template method pattern is used to define the program skeleton of an algorithm in an operation, deferring some steps to subclasses. It lets one redefine certain steps of an algorithm without changing the algorithm's structure. 652 | 653 | ### Example 654 | */ 655 | protocol WebsiteTemplate { 656 | func showPageContent() 657 | } 658 | 659 | extension WebsiteTemplate { 660 | func showPage() { 661 | print("Header") 662 | showPageContent() 663 | print("Footer") 664 | } 665 | } 666 | 667 | struct WelcomePage: WebsiteTemplate { 668 | func showPageContent() { 669 | print("Welcome") 670 | } 671 | } 672 | 673 | struct NewsPage: WebsiteTemplate { 674 | func showPageContent() { 675 | print("News") 676 | } 677 | } 678 | /*: 679 | ### Usage 680 | */ 681 | let welcomePage = WelcomePage() 682 | welcomePage.showPage() 683 | print("") 684 | 685 | let newsPage = NewsPage() 686 | newsPage.showPage() 687 | /*: 688 | 🏃 Visitor 689 | ---------- 690 | 691 | The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold. 692 | 693 | ### Example 694 | */ 695 | protocol Developer { 696 | func create(project: ProjectClass) 697 | func create(project: Database) 698 | func create(project: Test) 699 | } 700 | 701 | protocol ProjectElement { 702 | func beWritten(developer: Developer) 703 | } 704 | 705 | struct ProjectClass: ProjectElement { 706 | func beWritten(developer: Developer) { 707 | developer.create(project: self) 708 | } 709 | } 710 | 711 | struct Database: ProjectElement { 712 | func beWritten(developer: Developer) { 713 | developer.create(project: self) 714 | } 715 | } 716 | 717 | struct Test: ProjectElement { 718 | func beWritten(developer: Developer) { 719 | developer.create(project: self) 720 | } 721 | } 722 | 723 | struct Project: ProjectElement { 724 | var projectElements: [ProjectElement] = [ProjectClass(), Database(), Test()] 725 | 726 | func beWritten(developer: Developer) { 727 | for projectElement in projectElements { 728 | projectElement.beWritten(developer: developer) 729 | } 730 | } 731 | } 732 | 733 | struct JuniorDeveloper: Developer { 734 | func create(project: ProjectClass) { 735 | print("Writing poor class...") 736 | } 737 | 738 | func create(project: Database) { 739 | print("Drop database...") 740 | } 741 | 742 | func create(project: Test) { 743 | print("Creating not reliable test...") 744 | } 745 | } 746 | 747 | struct SeniorDeveloper: Developer { 748 | func create(project: ProjectClass) { 749 | print("Rewriting class after junior...") 750 | } 751 | 752 | func create(project: Database) { 753 | print("Fixing database...") 754 | } 755 | 756 | func create(project: Test) { 757 | print("Creating reliable test...") 758 | } 759 | } 760 | /*: 761 | ### Usage 762 | */ 763 | let project = Project() 764 | let junior = JuniorDeveloper() 765 | let senior = SeniorDeveloper() 766 | 767 | print("Junior in Action") 768 | project.beWritten(developer: junior) 769 | 770 | print("") 771 | 772 | print("Senior in Action") 773 | project.beWritten(developer: senior) 774 | /*: 775 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Visitor) 776 | */ 777 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | {project} Copyright (C) {year} {fullname} 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | 2 | Design Patterns implemented in Swift 3.1 3 | ======================================== 4 | A short cheat-sheet with Xcode 8.3.2 Playground ([Design-Patterns.zip](https://raw.githubusercontent.com/zsergey/Design-Patterns-In-Swift/master/Design-Patterns.zip)). 5 | 6 | 👷 Project maintained by: [@zsergey](http://twitter.com/zsergey) (Sergey Zapuhlyak) 7 | 8 | 🚀 How to generate README, Playground and zip from source: [GENERATE.md](https://github.com/zsergey/Design-Patterns-In-Swift/blob/master/GENERATE.md) 9 | 10 | ## Table of Contents 11 | 12 | * [Behavioral](#behavioral) 13 | * [Creational](#creational) 14 | * [Structural](#structural) 15 | 16 | 17 | ```swift 18 | 19 | ``` 20 | 21 | Behavioral 22 | ========== 23 | 24 | >In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication. 25 | > 26 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Behavioral_pattern) 27 | 28 | ```swift 29 | 30 | import Swift 31 | import Foundation 32 | ``` 33 | 34 | 🐝 Chain Of Responsibility 35 | -------------------------- 36 | 37 | The chain of responsibility pattern is used to process varied requests, each of which may be dealt with by a different handler. 38 | 39 | ### Example: 40 | 41 | ```swift 42 | 43 | protocol Notifier { 44 | var priority: Int { set get } 45 | var nextNotifier: Notifier? { set get } 46 | func write(_ message: String) 47 | } 48 | 49 | extension Notifier { 50 | func notifyManager(message: String, level: Int) { 51 | if level >= priority { 52 | write(message) 53 | } 54 | if let nextNotifie = self.nextNotifier { 55 | nextNotifie.notifyManager(message: message, level: level) 56 | } 57 | } 58 | } 59 | 60 | enum Priority { 61 | case routine 62 | case important 63 | case asSoonAsPossible 64 | } 65 | 66 | struct SimpleReportNotifier: Notifier { 67 | internal var nextNotifier: Notifier? 68 | internal var priority: Int 69 | 70 | func write(_ message: String) { 71 | print("Notifying using simple report: \(message)") 72 | } 73 | } 74 | 75 | struct EmailNotifier: Notifier { 76 | internal var nextNotifier: Notifier? 77 | internal var priority: Int 78 | 79 | func write(_ message: String) { 80 | print("Sending email: \(message)") 81 | } 82 | } 83 | 84 | struct SMSNotifier: Notifier { 85 | internal var nextNotifier: Notifier? 86 | internal var priority: Int 87 | 88 | func write(_ message: String) { 89 | print("Sending sms to manager: \(message)") 90 | } 91 | } 92 | ``` 93 | 94 | ### Usage 95 | 96 | ```swift 97 | 98 | let smsNotifier = SMSNotifier(nextNotifier: nil, priority: Priority.asSoonAsPossible.hashValue) 99 | let emailNotifier = EmailNotifier(nextNotifier: smsNotifier, priority: Priority.important.hashValue) 100 | let reportNotifier = SimpleReportNotifier(nextNotifier: emailNotifier, priority: Priority.routine.hashValue) 101 | 102 | reportNotifier.notifyManager(message: "Everything is OK", level: Priority.routine.hashValue) 103 | reportNotifier.notifyManager(message: "Something went wrong", level: Priority.important.hashValue) 104 | reportNotifier.notifyManager(message: "Houston, we've had a problem here!", level: Priority.asSoonAsPossible.hashValue) 105 | ``` 106 | 107 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Chain-Of-Responsibility) 108 | 109 | ```swift 110 | 111 | ``` 112 | 113 | 👫 Command 114 | ---------- 115 | 116 | The command pattern is used to express a request, including the call to be made and all of its required parameters, in a command object. The command may then be executed immediately or held for later use. 117 | 118 | ### Example: 119 | 120 | ```swift 121 | 122 | struct Database { 123 | func insert() { 124 | print("Inserting record...") 125 | } 126 | 127 | func update() { 128 | print("Updating record...") 129 | } 130 | 131 | func select() { 132 | print("Reading record...") 133 | } 134 | 135 | func delete() { 136 | print("Deleting record...") 137 | } 138 | } 139 | 140 | protocol Command { 141 | var database: Database { set get } 142 | func execute() 143 | } 144 | 145 | struct InsertCommand: Command { 146 | internal var database: Database 147 | 148 | func execute() { 149 | database.insert() 150 | } 151 | } 152 | 153 | struct UpdateCommand: Command { 154 | internal var database: Database 155 | 156 | func execute() { 157 | database.update() 158 | } 159 | } 160 | 161 | struct SelectCommand: Command { 162 | internal var database: Database 163 | 164 | func execute() { 165 | database.select() 166 | } 167 | } 168 | 169 | struct DeleteCommand: Command { 170 | internal var database: Database 171 | 172 | func execute() { 173 | database.delete() 174 | } 175 | } 176 | 177 | struct Developer { 178 | var insert, update, select, delete: Command 179 | 180 | func insertRecord() { 181 | insert.execute() 182 | } 183 | 184 | func updateRecord() { 185 | update.execute() 186 | } 187 | 188 | func selectRecord() { 189 | select.execute() 190 | } 191 | 192 | func deleteRecord() { 193 | delete.execute() 194 | } 195 | } 196 | ``` 197 | 198 | ### Usage: 199 | 200 | ```swift 201 | 202 | let database = Database() 203 | let insertCommand = InsertCommand(database: database) 204 | let updateCommand = UpdateCommand(database: database) 205 | let selectCommand = SelectCommand(database: database) 206 | let deleteCommand = DeleteCommand(database: database) 207 | 208 | let developer = Developer(insert: insertCommand, update: updateCommand, select: selectCommand, delete: deleteCommand) 209 | developer.insertRecord() 210 | developer.updateRecord() 211 | developer.selectRecord() 212 | developer.deleteRecord() 213 | ``` 214 | 215 | 🎶 Interpreter 216 | -------------- 217 | 218 | The interpreter pattern is used to evaluate sentences in a language. 219 | 220 | ### Example 221 | 222 | ```swift 223 | 224 | protocol Expression { 225 | func interpret(_ context: String) -> Bool 226 | } 227 | 228 | struct AndExpression: Expression { 229 | var expression1: Expression 230 | var expression2: Expression 231 | 232 | func interpret(_ context: String) -> Bool { 233 | return expression1.interpret(context) && expression2.interpret(context) 234 | } 235 | } 236 | 237 | struct OrExpression: Expression { 238 | var expression1: Expression 239 | var expression2: Expression 240 | 241 | func interpret(_ context: String) -> Bool { 242 | return expression1.interpret(context) || expression2.interpret(context) 243 | } 244 | } 245 | 246 | struct TerminalExpression: Expression { 247 | var data: String 248 | 249 | func interpret(_ context: String) -> Bool { 250 | return context.contains(data) 251 | } 252 | } 253 | ``` 254 | 255 | ### Usage 256 | 257 | ```swift 258 | 259 | struct Interpreter { 260 | static func getAppleExpression() -> Expression { 261 | let swift = TerminalExpression(data: "Swift") 262 | let objC = TerminalExpression(data: "Objective-C") 263 | return OrExpression(expression1: objC, expression2: swift) 264 | } 265 | 266 | static func getJavaEEExpression() -> Expression { 267 | let java = TerminalExpression(data: "Java") 268 | let spring = TerminalExpression(data: "Spring") 269 | return AndExpression(expression1: java, expression2: spring) 270 | } 271 | } 272 | 273 | let appleExpression = Interpreter.getAppleExpression() 274 | let javaExpression = Interpreter.getJavaEEExpression() 275 | print("Is Developer an Apple Developer \(appleExpression.interpret("Swift"))") 276 | print("Does developer knows Java EE \(javaExpression.interpret("Java Spring"))") 277 | ``` 278 | 279 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Interpreter) 280 | 281 | ```swift 282 | 283 | ``` 284 | 285 | 🍫 Iterator 286 | ----------- 287 | 288 | The iterator pattern is used to provide a standard interface for traversing a collection of items in an aggregate object without the need to understand its underlying structure. 289 | 290 | ### Example: 291 | 292 | ```swift 293 | 294 | protocol Iterator { 295 | func hasNext() -> Bool 296 | mutating func next() -> String 297 | } 298 | 299 | protocol Collection { 300 | func getIterator() -> Iterator 301 | } 302 | 303 | struct SwiftDeveloper: Collection { 304 | var name: String 305 | var skills: [String] 306 | 307 | private struct SkillIterator: Iterator { 308 | var index: Int 309 | var data: [String] 310 | func hasNext() -> Bool { 311 | return index < data.count 312 | } 313 | mutating func next() -> String { 314 | let result = data[index] 315 | index = index + 1 316 | return result 317 | } 318 | } 319 | 320 | func getIterator() -> Iterator { 321 | return SkillIterator(index: 0, data: skills) 322 | } 323 | } 324 | ``` 325 | 326 | ### Usage 327 | 328 | ```swift 329 | 330 | let skills = ["Swift", "ObjC", "Sketch", "PM"] 331 | let swiftDeveloper = SwiftDeveloper(name: "Sergey Zapuhlyak", skills: skills) 332 | var iterator = swiftDeveloper.getIterator() 333 | print("Developer \(swiftDeveloper.name)") 334 | print("Skills") 335 | while iterator.hasNext() { 336 | print("\(iterator.next())") 337 | } 338 | ``` 339 | 340 | 💐 Mediator 341 | ----------- 342 | 343 | The mediator pattern is used to reduce coupling between classes that communicate with each other. Instead of classes communicating directly, and thus requiring knowledge of their implementation, the classes send messages via a mediator object. 344 | 345 | ### Example 346 | 347 | ```swift 348 | 349 | protocol Chat { 350 | func sendMessage(_ message: String, from user: User) 351 | } 352 | 353 | protocol User { 354 | var ID: Int { set get } 355 | var name: String { set get } 356 | var chat: Chat { set get } 357 | func sendMessage(_ message: String) 358 | func getMessage(_ message: String) 359 | } 360 | 361 | struct Admin: User { 362 | internal var ID: Int 363 | internal var name: String 364 | internal var chat: Chat 365 | 366 | func sendMessage(_ message: String) { 367 | chat.sendMessage(message, from: self) 368 | } 369 | 370 | func getMessage(_ message: String) { 371 | print("\(name) received message: \(message)") 372 | } 373 | } 374 | 375 | struct Client: User { 376 | internal var ID: Int 377 | internal var name: String 378 | internal var chat: Chat 379 | 380 | func sendMessage(_ message: String) { 381 | chat.sendMessage(message, from: self) 382 | } 383 | 384 | func getMessage(_ message: String) { 385 | print("\(name) received message: \(message)") 386 | } 387 | } 388 | 389 | class Telegram: Chat { 390 | var admin: Admin? 391 | var clients: [Client]? 392 | 393 | func addClient(client: Client) { 394 | if clients == nil { 395 | clients = [Client]() 396 | } 397 | clients?.append(client) 398 | } 399 | 400 | func sendMessage(_ message: String, from user: User) { 401 | if let clients = clients { 402 | for client in clients { 403 | if client.ID != user.ID { 404 | client.getMessage(message) 405 | } 406 | } 407 | } 408 | 409 | admin?.getMessage(message) 410 | } 411 | } 412 | ``` 413 | 414 | ### Usage 415 | 416 | ```swift 417 | 418 | var telegram = Telegram() 419 | let admin = Admin(ID: 1, name: "Pavel Durov", chat: telegram) 420 | let zsergey = Client(ID: 2, name: "Sergey Zapuhlyak", chat: telegram) 421 | let azimin = Client(ID: 3, name: "Alex Zimin", chat: telegram) 422 | telegram.admin = admin 423 | telegram.addClient(client: zsergey) 424 | telegram.addClient(client: azimin) 425 | 426 | zsergey.sendMessage("Hello, I am Sergey Zapuhlyak") 427 | admin.sendMessage("I am Administrator!") 428 | ``` 429 | 430 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Mediator) 431 | 432 | ```swift 433 | 434 | ``` 435 | 436 | 💾 Memento 437 | ---------- 438 | 439 | The memento pattern is used to capture the current state of an object and store it in such a manner that it can be restored at a later time without breaking the rules of encapsulation. 440 | 441 | ### Example 442 | 443 | ```swift 444 | 445 | struct Project { 446 | var version: String 447 | var code: String 448 | 449 | func save() -> Save { 450 | return Save(version: version, code: code) 451 | } 452 | 453 | mutating func load(save: Save) { 454 | version = save.version 455 | code = save.code 456 | } 457 | 458 | func description() -> String { 459 | return "Project version = \(version): \n'\(code)'\n" 460 | } 461 | } 462 | 463 | struct Save { 464 | var version: String 465 | var code: String 466 | } 467 | 468 | struct GithubRepo { 469 | var save: Save 470 | } 471 | ``` 472 | 473 | ### Usage 474 | 475 | ```swift 476 | 477 | print("Creating new project. Version 1.0") 478 | var project = Project(version: "1.0", code: "let index = 0") 479 | print(project.description()) 480 | 481 | print("Saving current version to github") 482 | let github = GithubRepo(save: project.save()) 483 | 484 | print("Updating project to Version 1.1") 485 | print("Writing poor code...") 486 | print("Set version 1.1") 487 | project.version = "1.1" 488 | project.code = "let index = 0\nindex = 5" 489 | print(project.description()) 490 | 491 | print("Something went wrong") 492 | print("Rolling back to Version 1.0") 493 | 494 | project.load(save: github.save) 495 | print("Project after rollback") 496 | print(project.description()) 497 | ``` 498 | 499 | 👓 Observer 500 | ----------- 501 | 502 | The observer pattern is used to allow an object to publish changes to its state. 503 | Other objects subscribe to be immediately notified of any changes. 504 | 505 | ### Example 506 | 507 | ```swift 508 | 509 | protocol Observer { 510 | var name: String { get } 511 | 512 | func handleEvent(vacancies: [String]) 513 | } 514 | 515 | protocol Observed { 516 | mutating func addObserver(observer: Observer) 517 | mutating func removeObserver(observer: Observer) 518 | func notifyObservers() 519 | } 520 | 521 | struct Subscriber: Observer { 522 | var name: String 523 | 524 | func handleEvent(vacancies: [String]) { 525 | print("Dear \(name). We have some changes in vacancies:\n\(vacancies)\n") 526 | } 527 | } 528 | 529 | struct HeadHunter: Observed { 530 | var vacancies = [String]() 531 | var subscribers = [Observer]() 532 | 533 | mutating func addVacancy(vacancy: String) { 534 | vacancies.append(vacancy) 535 | notifyObservers() 536 | } 537 | 538 | mutating func removeVacancy(vacancy: String) { 539 | if let index = vacancies.index(of: vacancy) { 540 | vacancies.remove(at: index) 541 | notifyObservers() 542 | } 543 | } 544 | 545 | mutating func addObserver(observer: Observer) { 546 | subscribers.append(observer) 547 | } 548 | 549 | mutating func removeObserver(observer: Observer) { 550 | for index in 1...subscribers.count - 1 { 551 | let subscriber = subscribers[index] 552 | if subscriber.name == observer.name { 553 | subscribers.remove(at: index) 554 | break 555 | } 556 | } 557 | } 558 | 559 | func notifyObservers() { 560 | for subscriber in subscribers { 561 | subscriber.handleEvent(vacancies: vacancies) 562 | } 563 | } 564 | } 565 | ``` 566 | 567 | ### Usage 568 | 569 | ```swift 570 | 571 | var hh = HeadHunter() 572 | hh.addVacancy(vacancy: "Swift Developer") 573 | hh.addVacancy(vacancy: "ObjC Developer") 574 | 575 | let zsergey = Subscriber(name: "Sergey Zapuhlyak") 576 | let azimin = Subscriber(name: "Alex Zimin") 577 | 578 | hh.addObserver(observer: zsergey) 579 | hh.addObserver(observer: azimin) 580 | 581 | hh.addVacancy(vacancy: "C++ Developer") 582 | 583 | hh.removeObserver(observer: azimin) 584 | hh.removeVacancy(vacancy: "ObjC Developer") 585 | ``` 586 | 587 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Observer) 588 | 589 | ```swift 590 | 591 | ``` 592 | 593 | 🐉 State 594 | --------- 595 | 596 | The state pattern is used to alter the behaviour of an object as its internal state changes. 597 | The pattern allows the class for an object to apparently change at run-time. 598 | 599 | ### Example 600 | 601 | ```swift 602 | 603 | protocol Activity { 604 | func justDoIt() 605 | } 606 | 607 | struct Coding: Activity { 608 | func justDoIt() { 609 | print("Writing code...") 610 | } 611 | } 612 | 613 | struct Reading: Activity { 614 | func justDoIt() { 615 | print("Reading book...") 616 | } 617 | } 618 | 619 | struct Sleeping: Activity { 620 | func justDoIt() { 621 | print("Sleeping...") 622 | } 623 | } 624 | 625 | struct Training: Activity { 626 | func justDoIt() { 627 | print("Training...") 628 | } 629 | } 630 | 631 | struct Developer { 632 | var activity: Activity 633 | 634 | mutating func changeActivity() { 635 | if let _ = activity as? Sleeping { 636 | activity = Training() 637 | } else if let _ = activity as? Training { 638 | activity = Coding() 639 | } else if let _ = activity as? Coding { 640 | activity = Reading() 641 | } else if let _ = activity as? Reading { 642 | activity = Sleeping() 643 | } 644 | } 645 | 646 | func justDoIt() { 647 | activity.justDoIt() 648 | } 649 | } 650 | ``` 651 | 652 | ### Usage 653 | 654 | ```swift 655 | 656 | let activity = Sleeping() 657 | var developer = Developer(activity: activity) 658 | for i in 0..<10 { 659 | developer.justDoIt() 660 | developer.changeActivity() 661 | } 662 | ``` 663 | 664 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-State) 665 | 666 | ```swift 667 | 668 | ``` 669 | 670 | 💡 Strategy 671 | ----------- 672 | 673 | The strategy pattern is used to create an interchangeable family of algorithms from which the required process is chosen at run-time. 674 | 675 | ### Example 676 | 677 | ```swift 678 | 679 | protocol Activity { 680 | func justDoIt() 681 | } 682 | 683 | struct Coding: Activity { 684 | func justDoIt() { 685 | print("Writing code...") 686 | } 687 | } 688 | 689 | struct Reading: Activity { 690 | func justDoIt() { 691 | print("Reading book...") 692 | } 693 | } 694 | 695 | struct Sleeping: Activity { 696 | func justDoIt() { 697 | print("Sleeping...") 698 | } 699 | } 700 | 701 | struct Training: Activity { 702 | func justDoIt() { 703 | print("Training...") 704 | } 705 | } 706 | 707 | struct Developer { 708 | var activity: Activity 709 | 710 | func executeActivity() { 711 | activity.justDoIt() 712 | } 713 | } 714 | ``` 715 | 716 | ### Usage 717 | 718 | ```swift 719 | 720 | var developer = Developer(activity: Sleeping()) 721 | developer.executeActivity() 722 | 723 | developer.activity = Training() 724 | developer.executeActivity() 725 | 726 | developer.activity = Coding() 727 | developer.executeActivity() 728 | 729 | developer.activity = Reading() 730 | developer.executeActivity() 731 | 732 | developer.activity = Sleeping() 733 | developer.executeActivity() 734 | ``` 735 | 736 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Strategy) 737 | 738 | ```swift 739 | 740 | ``` 741 | 742 | 🐾 Template Method 743 | ---------- 744 | 745 | The template method pattern is used to define the program skeleton of an algorithm in an operation, deferring some steps to subclasses. It lets one redefine certain steps of an algorithm without changing the algorithm's structure. 746 | 747 | ### Example 748 | 749 | ```swift 750 | 751 | protocol WebsiteTemplate { 752 | func showPageContent() 753 | } 754 | 755 | extension WebsiteTemplate { 756 | func showPage() { 757 | print("Header") 758 | showPageContent() 759 | print("Footer") 760 | } 761 | } 762 | 763 | struct WelcomePage: WebsiteTemplate { 764 | func showPageContent() { 765 | print("Welcome") 766 | } 767 | } 768 | 769 | struct NewsPage: WebsiteTemplate { 770 | func showPageContent() { 771 | print("News") 772 | } 773 | } 774 | ``` 775 | 776 | ### Usage 777 | 778 | ```swift 779 | 780 | let welcomePage = WelcomePage() 781 | welcomePage.showPage() 782 | print("") 783 | 784 | let newsPage = NewsPage() 785 | newsPage.showPage() 786 | ``` 787 | 788 | 🏃 Visitor 789 | ---------- 790 | 791 | The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold. 792 | 793 | ### Example 794 | 795 | ```swift 796 | 797 | protocol Developer { 798 | func create(project: ProjectClass) 799 | func create(project: Database) 800 | func create(project: Test) 801 | } 802 | 803 | protocol ProjectElement { 804 | func beWritten(developer: Developer) 805 | } 806 | 807 | struct ProjectClass: ProjectElement { 808 | func beWritten(developer: Developer) { 809 | developer.create(project: self) 810 | } 811 | } 812 | 813 | struct Database: ProjectElement { 814 | func beWritten(developer: Developer) { 815 | developer.create(project: self) 816 | } 817 | } 818 | 819 | struct Test: ProjectElement { 820 | func beWritten(developer: Developer) { 821 | developer.create(project: self) 822 | } 823 | } 824 | 825 | struct Project: ProjectElement { 826 | var projectElements: [ProjectElement] = [ProjectClass(), Database(), Test()] 827 | 828 | func beWritten(developer: Developer) { 829 | for projectElement in projectElements { 830 | projectElement.beWritten(developer: developer) 831 | } 832 | } 833 | } 834 | 835 | struct JuniorDeveloper: Developer { 836 | func create(project: ProjectClass) { 837 | print("Writing poor class...") 838 | } 839 | 840 | func create(project: Database) { 841 | print("Drop database...") 842 | } 843 | 844 | func create(project: Test) { 845 | print("Creating not reliable test...") 846 | } 847 | } 848 | 849 | struct SeniorDeveloper: Developer { 850 | func create(project: ProjectClass) { 851 | print("Rewriting class after junior...") 852 | } 853 | 854 | func create(project: Database) { 855 | print("Fixing database...") 856 | } 857 | 858 | func create(project: Test) { 859 | print("Creating reliable test...") 860 | } 861 | } 862 | ``` 863 | 864 | ### Usage 865 | 866 | ```swift 867 | 868 | let project = Project() 869 | let junior = JuniorDeveloper() 870 | let senior = SeniorDeveloper() 871 | 872 | print("Junior in Action") 873 | project.beWritten(developer: junior) 874 | 875 | print("") 876 | 877 | print("Senior in Action") 878 | project.beWritten(developer: senior) 879 | ``` 880 | 881 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Visitor) 882 | 883 | ```swift 884 | 885 | ``` 886 | 887 | Creational 888 | ========== 889 | 890 | > In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. 891 | > 892 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Creational_pattern) 893 | 894 | ```swift 895 | 896 | import Swift 897 | import Foundation 898 | ``` 899 | 900 | 🌰 Abstract Factory 901 | ------------------- 902 | 903 | The abstract factory pattern is used to provide a client with a set of related or dependant objects. 904 | The "family" of objects created by the factory are determined at run-time. 905 | 906 | ### Example 907 | 908 | ```swift 909 | 910 | protocol Developer { 911 | func writeCode() 912 | } 913 | 914 | protocol Tester { 915 | func testCode() 916 | } 917 | 918 | protocol ProjectManager { 919 | func manageProject() 920 | } 921 | 922 | protocol ProjectTeamFactory { 923 | var developer: Developer { get } 924 | var tester: Tester { get } 925 | var projectManager: ProjectManager { get } 926 | } 927 | 928 | // Team of Bank. 929 | struct SwiftDeveloper: Developer { 930 | func writeCode() { 931 | print("Swift developer writes Swift code...") 932 | } 933 | } 934 | 935 | struct QATester: Tester { 936 | func testCode() { 937 | print("QA tester tests banking code...") 938 | } 939 | } 940 | 941 | struct BankingPM: ProjectManager { 942 | func manageProject() { 943 | print("BankingPM manages banking project...") 944 | } 945 | } 946 | 947 | struct BankingTeamFactory: ProjectTeamFactory { 948 | var developer: Developer { 949 | return SwiftDeveloper() 950 | } 951 | var tester: Tester { 952 | return QATester() 953 | } 954 | var projectManager: ProjectManager { 955 | return BankingPM() 956 | } 957 | } 958 | 959 | // Team of Website. 960 | struct PhpDeveloper: Developer { 961 | func writeCode() { 962 | print("Php developer writes php code...") 963 | } 964 | } 965 | 966 | struct ManualTester: Tester { 967 | func testCode() { 968 | print("Manual tester tests Website...") 969 | } 970 | } 971 | 972 | struct WebsitePM: ProjectManager { 973 | func manageProject() { 974 | print("WebsitePM manages Website project...") 975 | } 976 | } 977 | 978 | struct WebsiteTeamFactory: ProjectTeamFactory { 979 | var developer: Developer { 980 | return PhpDeveloper() 981 | } 982 | var tester: Tester { 983 | return ManualTester() 984 | } 985 | var projectManager: ProjectManager { 986 | return WebsitePM() 987 | } 988 | } 989 | 990 | // Projects. 991 | enum Projects { 992 | case bankBusinessOnline 993 | case auctionSite 994 | 995 | var name: String { 996 | switch self { 997 | case .bankBusinessOnline: 998 | return "Bank business online" 999 | case .auctionSite: 1000 | return "Auction site" 1001 | } 1002 | } 1003 | 1004 | var factory: ProjectTeamFactory { 1005 | switch self { 1006 | case .bankBusinessOnline: 1007 | return BankingTeamFactory() 1008 | case .auctionSite: 1009 | return WebsiteTeamFactory() 1010 | } 1011 | } 1012 | 1013 | func createProject() { 1014 | print("Создание проекта \(name)") 1015 | let projectFactory = factory 1016 | projectFactory.developer.writeCode() 1017 | projectFactory.tester.testCode() 1018 | projectFactory.projectManager.manageProject() 1019 | } 1020 | } 1021 | ``` 1022 | 1023 | ### Usage 1024 | 1025 | ```swift 1026 | 1027 | Projects.bankBusinessOnline.createProject() 1028 | Projects.auctionSite.createProject() 1029 | ``` 1030 | 1031 | 👷 Builder 1032 | ---------- 1033 | 1034 | The builder pattern is used to create complex objects with constituent parts that must be created in the same order or using a specific algorithm. 1035 | An external class controls the construction algorithm. 1036 | 1037 | ### Example 1038 | 1039 | ```swift 1040 | 1041 | enum Cms { 1042 | case wordpress 1043 | case alifresco 1044 | } 1045 | 1046 | struct Website { 1047 | var name: String? 1048 | var cms: Cms? 1049 | var price: Int? 1050 | 1051 | func printWebsite(){ 1052 | guard let name = name, let cms = cms, let price = price else { 1053 | return 1054 | } 1055 | print("Name \(name), cms \(cms), price \(price)") 1056 | } 1057 | } 1058 | 1059 | protocol WebsiteBuilder { 1060 | var website: Website? { set get } 1061 | func createWebsite() 1062 | func buildName() 1063 | func buildCms() 1064 | func buildPrice() 1065 | } 1066 | 1067 | class VisitCardWebsiteBuilder: WebsiteBuilder { 1068 | internal var website: Website? 1069 | 1070 | internal func createWebsite() { 1071 | self.website = Website() 1072 | } 1073 | 1074 | internal func buildName() { 1075 | self.website?.name = "Visit Card" 1076 | } 1077 | 1078 | internal func buildCms() { 1079 | self.website?.cms = .wordpress 1080 | } 1081 | 1082 | internal func buildPrice() { 1083 | self.website?.price = 500 1084 | } 1085 | } 1086 | 1087 | class EnterpriseWebsiteBuilder: WebsiteBuilder { 1088 | internal var website: Website? 1089 | 1090 | internal func createWebsite() { 1091 | self.website = Website() 1092 | } 1093 | 1094 | internal func buildName() { 1095 | self.website?.name = "Enterprise website" 1096 | } 1097 | 1098 | internal func buildCms() { 1099 | self.website?.cms = .alifresco 1100 | } 1101 | 1102 | internal func buildPrice() { 1103 | self.website?.price = 10000 1104 | } 1105 | } 1106 | 1107 | struct Director { 1108 | var builder: WebsiteBuilder 1109 | 1110 | func buildWebsite() -> Website { 1111 | builder.createWebsite() 1112 | builder.buildName() 1113 | builder.buildCms() 1114 | builder.buildPrice() 1115 | return builder.website! 1116 | } 1117 | } 1118 | ``` 1119 | 1120 | ### Usage 1121 | 1122 | ```swift 1123 | 1124 | let director = Director(builder: EnterpriseWebsiteBuilder()) 1125 | let website = director.buildWebsite() 1126 | website.printWebsite() 1127 | ``` 1128 | 1129 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Builder) 1130 | 1131 | ```swift 1132 | 1133 | ``` 1134 | 1135 | 🏭 Factory Method 1136 | ----------------- 1137 | 1138 | The factory pattern is used to replace class constructors, abstracting the process of object generation so that the type of the object instantiated can be determined at run-time. 1139 | 1140 | ### Example 1141 | 1142 | ```swift 1143 | 1144 | protocol Developer { 1145 | func writeCode() 1146 | } 1147 | 1148 | struct ObjCDeveloper: Developer { 1149 | func writeCode() { 1150 | print("ObjC developer writes Objective C code...") 1151 | } 1152 | } 1153 | 1154 | struct SwiftDeveloper: Developer { 1155 | func writeCode() { 1156 | print("Swift developer writes Swift code...") 1157 | } 1158 | } 1159 | 1160 | protocol DeveloperFactory { 1161 | func newDeveloper() -> Developer 1162 | } 1163 | 1164 | struct ObjCDeveloperFactory: DeveloperFactory { 1165 | func newDeveloper() -> Developer { 1166 | return ObjCDeveloper() 1167 | } 1168 | } 1169 | 1170 | struct SwiftDeveloperFactory: DeveloperFactory { 1171 | func newDeveloper() -> Developer { 1172 | return SwiftDeveloper() 1173 | } 1174 | } 1175 | 1176 | enum Languages { 1177 | case objC 1178 | case swift 1179 | 1180 | var factory: DeveloperFactory { 1181 | switch self { 1182 | case .objC: 1183 | return ObjCDeveloperFactory() 1184 | case .swift: 1185 | return SwiftDeveloperFactory() 1186 | } 1187 | } 1188 | } 1189 | ``` 1190 | 1191 | ### Usage 1192 | 1193 | ```swift 1194 | 1195 | let developer = Languages.swift.factory.newDeveloper() 1196 | developer.writeCode() 1197 | ``` 1198 | 1199 | 🃏 Prototype 1200 | ------------ 1201 | 1202 | The prototype pattern is used to instantiate a new object by copying all of the properties of an existing object, creating an independent clone. 1203 | This practise is particularly useful when the construction of a new object is inefficient. 1204 | 1205 | ### Example 1206 | 1207 | ```swift 1208 | 1209 | protocol Copyable { 1210 | func copy() -> Any 1211 | } 1212 | 1213 | struct Project: Copyable { 1214 | var id: Int 1215 | var name: String 1216 | var source: String 1217 | 1218 | func copy() -> Any { 1219 | let object = Project(id: id, name: name, source: source) 1220 | return object 1221 | } 1222 | } 1223 | 1224 | struct ProjectFactory { 1225 | var project: Project 1226 | func cloneProject() -> Project { 1227 | return project.copy() as! Project 1228 | } 1229 | } 1230 | ``` 1231 | 1232 | ### Usage 1233 | 1234 | ```swift 1235 | 1236 | let master = Project(id: 1, name: "Playground.swift", source: "let sourceCode = SourceCode()") 1237 | let factory = ProjectFactory(project: master) 1238 | let masterClone = factory.cloneProject() 1239 | ``` 1240 | 1241 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Prototype) 1242 | 1243 | ```swift 1244 | 1245 | ``` 1246 | 1247 | 💍 Singleton 1248 | ------------ 1249 | 1250 | The singleton pattern ensures that only one object of a particular class is ever created. 1251 | All further references to objects of the singleton class refer to the same underlying instance. 1252 | There are very few applications, do not overuse this pattern! 1253 | 1254 | ### Example: 1255 | 1256 | ```swift 1257 | 1258 | struct Game { 1259 | static let sharedGame = Game() 1260 | 1261 | private init() { 1262 | 1263 | } 1264 | } 1265 | ``` 1266 | 1267 | ### Usage: 1268 | 1269 | ```swift 1270 | 1271 | let game = Game.sharedGame 1272 | ``` 1273 | 1274 | Structural 1275 | ========== 1276 | 1277 | >In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships between entities. 1278 | > 1279 | >**Source:** [wikipedia.org](http://en.wikipedia.org/wiki/Structural_pattern) 1280 | 1281 | ```swift 1282 | 1283 | import Swift 1284 | import Foundation 1285 | ``` 1286 | 1287 | 🔌 Adapter 1288 | ---------- 1289 | 1290 | The adapter pattern is used to provide a link between two otherwise incompatible types by wrapping the "adaptee" with a class that supports the interface required by the client. 1291 | 1292 | ### Example 1293 | 1294 | ```swift 1295 | 1296 | protocol Database { 1297 | func insert() 1298 | func update() 1299 | func select() 1300 | func remove() 1301 | } 1302 | 1303 | class SwiftApp { 1304 | func saveObject() { 1305 | print("Saving Swift Object...") 1306 | } 1307 | 1308 | func updateObject() { 1309 | print("Updating Swift Object...") 1310 | } 1311 | 1312 | func loadObject() { 1313 | print("Loading Swift Object...") 1314 | } 1315 | 1316 | func deleteObject() { 1317 | print("Deleting Swift Object...") 1318 | } 1319 | } 1320 | 1321 | class AdapterSwiftAppToDatabase: SwiftApp, Database { 1322 | func insert() { 1323 | saveObject() 1324 | } 1325 | 1326 | func update() { 1327 | updateObject() 1328 | } 1329 | 1330 | func select() { 1331 | loadObject() 1332 | } 1333 | 1334 | func remove() { 1335 | deleteObject() 1336 | } 1337 | } 1338 | 1339 | struct DatabaseManager { 1340 | var database: Database 1341 | func run() { 1342 | database.insert() 1343 | database.update() 1344 | database.select() 1345 | database.remove() 1346 | } 1347 | } 1348 | ``` 1349 | 1350 | ### Usage 1351 | 1352 | ```swift 1353 | 1354 | let databaseManager = DatabaseManager(database: AdapterSwiftAppToDatabase()) 1355 | databaseManager.run() 1356 | ``` 1357 | 1358 | >**Further Examples:** [Design Patterns in Swift](https://github.com/kingreza/Swift-Adapter) 1359 | 1360 | ```swift 1361 | 1362 | ``` 1363 | 1364 | 🌉 Bridge 1365 | ---------- 1366 | 1367 | The bridge pattern is used to separate the abstract elements of a class from the implementation details, providing the means to replace the implementation details without modifying the abstraction. 1368 | 1369 | ### Example 1370 | 1371 | ```swift 1372 | 1373 | protocol Developer { 1374 | func writeCode() 1375 | } 1376 | 1377 | protocol Program { 1378 | var developer: Developer { get set } 1379 | func develop() 1380 | } 1381 | 1382 | struct SwiftDeveloper: Developer { 1383 | func writeCode() { 1384 | print("Swift Developer writes Swift code...") 1385 | } 1386 | } 1387 | 1388 | struct ObjCDeveloper: Developer { 1389 | func writeCode() { 1390 | print("ObjC Developer writes Objective-C code...") 1391 | } 1392 | } 1393 | 1394 | struct BankSystem: Program { 1395 | var developer: Developer 1396 | 1397 | func develop() { 1398 | print("Bank System development in progress...") 1399 | developer.writeCode() 1400 | } 1401 | } 1402 | 1403 | struct StockExchange: Program { 1404 | var developer: Developer 1405 | 1406 | func develop() { 1407 | print("Stock Exchange development in progress...") 1408 | developer.writeCode() 1409 | } 1410 | } 1411 | ``` 1412 | 1413 | ### Usage 1414 | 1415 | ```swift 1416 | 1417 | let programs: [Program] = [BankSystem(developer: ObjCDeveloper()), 1418 | StockExchange(developer: SwiftDeveloper())] 1419 | for program in programs { 1420 | program.develop() 1421 | } 1422 | ``` 1423 | 1424 | 🌿 Composite 1425 | ------------- 1426 | 1427 | The composite pattern is used to create hierarchical, recursive tree structures of related objects where any element of the structure may be accessed and utilised in a standard manner. 1428 | 1429 | ### Example 1430 | 1431 | ```swift 1432 | 1433 | protocol Developer { 1434 | func writeCode() 1435 | } 1436 | 1437 | protocol Team { 1438 | var developers: [Developer] { set get } 1439 | func addDeveloper(developer: Developer) 1440 | func createProject() 1441 | } 1442 | 1443 | struct SwiftDeveloper: Developer{ 1444 | func writeCode() { 1445 | print("Swift Developer writes Swift code...") 1446 | } 1447 | } 1448 | 1449 | struct ObjCDeveloper: Developer{ 1450 | func writeCode() { 1451 | print("ObjC Developer writes Objective-C code...") 1452 | } 1453 | } 1454 | 1455 | class BankTeam: Team { 1456 | var developers = [Developer]() 1457 | 1458 | func addDeveloper(developer: Developer) { 1459 | developers.append(developer) 1460 | } 1461 | 1462 | func createProject() { 1463 | for developer in developers { 1464 | developer.writeCode() 1465 | } 1466 | } 1467 | } 1468 | ``` 1469 | 1470 | ### Usage: 1471 | 1472 | ```swift 1473 | 1474 | let team = BankTeam() 1475 | team.addDeveloper(developer: ObjCDeveloper()) 1476 | team.addDeveloper(developer: ObjCDeveloper()) 1477 | team.addDeveloper(developer: ObjCDeveloper()) 1478 | team.addDeveloper(developer: ObjCDeveloper()) 1479 | team.addDeveloper(developer: SwiftDeveloper()) 1480 | team.createProject() 1481 | ``` 1482 | 1483 | 🍧 Decorator 1484 | ------------ 1485 | 1486 | The decorator pattern is used to extend or alter the functionality of objects at run- time by wrapping them in an object of a decorator class. 1487 | This provides a flexible alternative to using inheritance to modify behaviour. 1488 | 1489 | ### Example 1490 | 1491 | ```swift 1492 | 1493 | protocol Developer { 1494 | func makeJob() -> String 1495 | } 1496 | 1497 | struct SwiftDeveloper: Developer { 1498 | func makeJob() -> String { 1499 | return "Write Swift code" 1500 | } 1501 | } 1502 | 1503 | class DeveloperDecorator: Developer { 1504 | var developer: Developer 1505 | func makeJob() -> String { 1506 | return developer.makeJob() 1507 | } 1508 | init(developer: Developer) { 1509 | self.developer = developer 1510 | } 1511 | } 1512 | 1513 | class SeniorSwiftDeveloper: DeveloperDecorator { 1514 | let codeReview = "Make code review" 1515 | override func makeJob() -> String { 1516 | return super.makeJob() + " & " + codeReview 1517 | } 1518 | } 1519 | 1520 | class SwiftTeamLead: DeveloperDecorator { 1521 | let sendWeekReport = "Send week report" 1522 | override func makeJob() -> String { 1523 | return super.makeJob() + " & " + sendWeekReport 1524 | } 1525 | } 1526 | ``` 1527 | 1528 | ### Usage: 1529 | 1530 | ```swift 1531 | 1532 | let developer = SwiftTeamLead(developer: SeniorSwiftDeveloper(developer: SwiftDeveloper())) 1533 | print(developer.makeJob()) 1534 | ``` 1535 | 1536 | 🎁 Façade 1537 | --------- 1538 | 1539 | The facade pattern is used to define a simplified interface to a more complex subsystem. 1540 | 1541 | ### Example 1542 | 1543 | ```swift 1544 | 1545 | class Job { 1546 | func doJob() { 1547 | print("Job is progress...") 1548 | } 1549 | } 1550 | 1551 | class BugTracker { 1552 | var isActiveSprint = false 1553 | 1554 | func startSprint() { 1555 | print("Sprint is active") 1556 | isActiveSprint = true 1557 | } 1558 | 1559 | func stopSprint() { 1560 | print("Sprint is not active") 1561 | isActiveSprint = false 1562 | } 1563 | } 1564 | 1565 | class Developer { 1566 | func doJobBeforeDeadline(bugTracker: BugTracker) { 1567 | if bugTracker.isActiveSprint { 1568 | print("Developer is solving problems...") 1569 | } else { 1570 | print("Developer is reading the news...") 1571 | } 1572 | } 1573 | } 1574 | 1575 | class Workflow { 1576 | let developer = Developer() 1577 | let job = Job() 1578 | let bugTracker = BugTracker() 1579 | func solveProblems() { 1580 | job.doJob() 1581 | bugTracker.startSprint() 1582 | developer.doJobBeforeDeadline(bugTracker: bugTracker) 1583 | } 1584 | } 1585 | ``` 1586 | 1587 | ### Usage 1588 | 1589 | ```swift 1590 | 1591 | let workflow = Workflow() 1592 | workflow.solveProblems() 1593 | ``` 1594 | 1595 | ## 🍃 Flyweight 1596 | The flyweight pattern is used to minimize memory usage or computational expenses by sharing as much as possible with other similar objects. 1597 | ### Example 1598 | 1599 | ```swift 1600 | 1601 | protocol Developer { 1602 | func writeCode() 1603 | } 1604 | 1605 | struct SwiftDeveloper: Developer { 1606 | func writeCode() { 1607 | print("Swift Developer writes Swift code...") 1608 | } 1609 | } 1610 | 1611 | struct ObjCDeveloper: Developer { 1612 | func writeCode() { 1613 | print("ObjC Developer writes Objective-C code...") 1614 | } 1615 | } 1616 | 1617 | enum Languages: String { 1618 | case Swift 1619 | case ObjC 1620 | 1621 | var description: String { 1622 | return self.rawValue 1623 | } 1624 | } 1625 | 1626 | struct DeveloperFactory { 1627 | private var developers = [String: Developer]() 1628 | 1629 | mutating func developer(by language: Languages) -> Developer { 1630 | if let value = developers[language.description] { 1631 | return value 1632 | } else { 1633 | var value: Developer? = nil 1634 | print("Hiring \(language.description) developer ") 1635 | switch language { 1636 | case .Swift: 1637 | value = SwiftDeveloper() 1638 | case .ObjC: 1639 | value = ObjCDeveloper() 1640 | } 1641 | developers[language.description] = value 1642 | return value! 1643 | } 1644 | } 1645 | } 1646 | ``` 1647 | 1648 | ### Usage 1649 | 1650 | ```swift 1651 | 1652 | var developerFactory = DeveloperFactory() 1653 | var developers = [Developer]() 1654 | developers.append(developerFactory.developer(by: .Swift)) 1655 | developers.append(developerFactory.developer(by: .Swift)) 1656 | developers.append(developerFactory.developer(by: .Swift)) 1657 | developers.append(developerFactory.developer(by: .ObjC)) 1658 | developers.append(developerFactory.developer(by: .ObjC)) 1659 | developers.append(developerFactory.developer(by: .ObjC)) 1660 | for developer in developers { 1661 | developer.writeCode() 1662 | } 1663 | ``` 1664 | 1665 | ☔ Proxy 1666 | ------------------ 1667 | 1668 | The proxy pattern is used to provide a surrogate or placeholder object, which references an underlying object. 1669 | 1670 | ### Example 1671 | 1672 | ```swift 1673 | 1674 | protocol Project { 1675 | func run() 1676 | } 1677 | 1678 | struct RealProject: Project { 1679 | var url: String 1680 | 1681 | func load() { 1682 | print("Loading project from url \(url) ...") 1683 | } 1684 | 1685 | init(url: String) { 1686 | self.url = url 1687 | load() 1688 | } 1689 | 1690 | func run() { 1691 | print("Running project \(url) ...") 1692 | } 1693 | } 1694 | 1695 | class ProxyProject: Project { 1696 | var url: String 1697 | var realProject: RealProject? 1698 | 1699 | func run() { 1700 | if realProject == nil { 1701 | realProject = RealProject(url: url) 1702 | } 1703 | realProject!.run() 1704 | } 1705 | 1706 | init(url: String) { 1707 | self.url = url 1708 | } 1709 | } 1710 | ``` 1711 | 1712 | ### Usage 1713 | 1714 | ```swift 1715 | 1716 | var project = ProxyProject(url: "https://github.com/zsergey/realProject") 1717 | project.run() 1718 | ``` 1719 | 1720 | 1721 | Info 1722 | ==== 1723 | 1724 | 📖 Descriptions from: [Gang of Four Design Patterns Reference Sheet](http://www.blackwasp.co.uk/GangOfFour.aspx) 1725 | 1726 | 1727 | ```swift 1728 | --------------------------------------------------------------------------------