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Added Memento Pattern
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‎Design-Patterns.playground.zip

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‎Design-Patterns.playground/Documentation/section-59.html

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<section class="section">
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<h2 id="-iterator">🚧 Iterator</h2>
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<h2 id="-mediator">🚧 Mediator</h2>
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<h2 id="-memento">🚧 Memento</h2>
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<h2 id="-observer">👓 Observer</h2>
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<h2 id="-memento">💾 Memento</h2>
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</section>
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</div>

‎Design-Patterns.playground/Documentation/section-61.html

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<body>
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<div class="content-wrapper">
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<section class="section">
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<p><strong>Usage:</strong></p>
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<p><strong><em>Usage:</em></strong></p>
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</section>
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</div>

‎Design-Patterns.playground/Documentation/section-63.html

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<body>
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<div class="content-wrapper">
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<section class="section">
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<h2 id="-state">🐉 State</h2>
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<h2 id="-observer">👓 Observer</h2>
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</section>
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</div>

‎Design-Patterns.playground/Documentation/section-67.html

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<body>
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<div class="content-wrapper">
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<section class="section">
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<h2 id="-strategy">💡 Strategy</h2>
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<h2 id="-state">🐉 State</h2>
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</section>
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</div>

‎Design-Patterns.playground/Documentation/section-71.html

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<body>
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<div class="content-wrapper">
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<section class="section">
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<h2 id="-visitor">🏃 Visitor</h2>
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<h2 id="-strategy">💡 Strategy</h2>
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</section>
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</div>

‎Design-Patterns.playground/Documentation/section-75.html

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<body>
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<div class="content-wrapper">
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<section class="section">
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<h1 id="info">Info</h1>
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<p>🍺 Playground generated with: <a href="https://github.com/jas/swift-playground-builder">Swift Playground Builder</a> by <a href="http://twitter.com/jasonsandmeyer">@jasonsandmeyer</a></p>
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<p>🚀 How to generate playground (+zip) from this README: <a href="https://github.com/ochococo/Design-Patterns-In-Swift/blob/master/GENERATE.markdown">GENERATE.markdown</a></p>
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<h2 id="-visitor">🏃 Visitor</h2>
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</section>
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</div>

‎Design-Patterns.playground/Documentation/section-77.html

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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Section 78</title>
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<meta id="xcode-display" name="xcode-display" content="render">
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<meta name="apple-mobile-web-app-capable" content="yes">
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<meta name="viewport" content="width=device-width, maximum-scale=1.0">
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<link rel="stylesheet" type="text/css" href="stylesheet.css">
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</head>
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<body>
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<div class="content-wrapper">
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<section class="section">
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<p><strong>Usage:</strong></p>
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</section>
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</div>
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</body>
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</html>

‎Design-Patterns.playground/Documentation/section-79.html

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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Section 80</title>
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<meta id="xcode-display" name="xcode-display" content="render">
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<meta name="apple-mobile-web-app-capable" content="yes">
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<meta name="viewport" content="width=device-width, maximum-scale=1.0">
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<link rel="stylesheet" type="text/css" href="stylesheet.css">
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</head>
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<body>
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<div class="content-wrapper">
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<section class="section">
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<h1 id="info">Info</h1>
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<p>🍺 Playground generated with: <a href="https://github.com/jas/swift-playground-builder">Swift Playground Builder</a> by <a href="http://twitter.com/jasonsandmeyer">@jasonsandmeyer</a></p>
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<p>🚀 How to generate playground (+zip) from this README: <a href="https://github.com/ochococo/Design-Patterns-In-Swift/blob/master/GENERATE.markdown">GENERATE.markdown</a></p>
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</section>
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</div>
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</body>
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</html>

‎Design-Patterns.playground/contents.xcplayground

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</code>
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<documentation relative-path="section-75.html">
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</documentation>
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<code source-file-name="section-76.swift">
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</code>
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<documentation relative-path="section-77.html">
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</documentation>
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<code source-file-name="section-78.swift">
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</code>
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<documentation relative-path="section-79.html">
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</documentation>
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</sections>
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</playground>

‎Design-Patterns.playground/section-60.swift

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class StepCounter {
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var totalSteps: Int = 0 {
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willSet(newTotalSteps) {
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println("About to set totalSteps to \(newTotalSteps)")
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}
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didSet {
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if totalSteps > oldValue {
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println("Added \(totalSteps - oldValue) steps")
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}
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}
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typealias Memento = Dictionary<NSObject,AnyObject>
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/**
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* Originator
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*/
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class GameState {
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var gameLevel:Int = 1
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var playerScore:Int = 0
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func saveToMemeto() -> Memento { return ["gameLevel":gameLevel,"playerScore":playerScore] }
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func restoreFromMemeto(memento:Memento) {
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gameLevel = memento["gameLevel"]! as Int
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playerScore = memento["playerScore"]! as Int
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}
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}
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/**
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* Caretaker
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*/
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class CheckPoint {
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class func saveState(memento:Memento,keyName:String = "gameState"){
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let defaults:NSUserDefaults = NSUserDefaults.standardUserDefaults()
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defaults.setObject(memento , forKey:keyName)
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defaults.synchronize()
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}
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class func restorePreviousState(keyName:String = "gameState") -> Memento{
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let defaults:NSUserDefaults = NSUserDefaults.standardUserDefaults()
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return defaults.objectForKey(keyName) as Memento
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}
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}

‎Design-Patterns.playground/section-62.swift

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let stepCounter = StepCounter()
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stepCounter.totalSteps = 200
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// About to set totalSteps to 200
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// Added 200 steps
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stepCounter.totalSteps = 360
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// About to set totalSteps to 360
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// Added 160 steps
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stepCounter.totalSteps = 896
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// About to set totalSteps to 896
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// Added 536 steps
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var gameState = GameState()
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gameState.gameLevel = 2
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gameState.playerScore = 200
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//saves state:{gameLevel 2 playerScore 200}
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CheckPoint.saveState(gameState.saveToMemeto())
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gameState.gameLevel = 3
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gameState.gameLevel = 250
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//restores state:{gameLevel 2 playerScore 200}
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gameState.restoreFromMemeto(CheckPoint.restorePreviousState())
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gameState.gameLevel = 4
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//saves state - gameState2:{gameLevel 4 playerScore 200}
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CheckPoint.saveState(gameState.saveToMemeto(),keyName: "gameState2")
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gameState.gameLevel = 5
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gameState.playerScore = 300
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//saves state - gameState3:{gameLevel 5 playerScore 300}
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CheckPoint.saveState(gameState.saveToMemeto(),keyName: "gameState3")
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//restores state - gameState2:{gameLevel 4 playerScore 200}
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gameState.restoreFromMemeto(CheckPoint.restorePreviousState(keyName: "gameState2"))

‎Design-Patterns.playground/section-64.swift

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class Context {
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private var state: State = UnauthorizedState()
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var isAuthorized: Bool {
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get { return state.isAuthorized(self) }
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}
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var userId: String? {
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get { return state.userId(self) }
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class StepCounter {
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var totalSteps: Int = 0 {
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willSet(newTotalSteps) {
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println("About to set totalSteps to \(newTotalSteps)")
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}
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didSet {
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if totalSteps > oldValue {
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println("Added \(totalSteps - oldValue) steps")
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}
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}
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}
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func changeStateToAuthorized(#userId: String) {
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state = AuthorizedState(userId: userId)
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}
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func changeStateToUnauthorized() {
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state = UnauthorizedState()
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}
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}
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protocol State {
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func isAuthorized(context: Context) -> Bool
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func userId(context: Context) -> String?
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}
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class UnauthorizedState: State {
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func isAuthorized(context: Context) -> Bool { return false }
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func userId(context: Context) -> String? { return nil }
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}
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class AuthorizedState: State {
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let userId: String
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init(userId: String) { self.userId = userId }
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func isAuthorized(context: Context) -> Bool { return true }
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func userId(context: Context) -> String? { return userId }
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}

‎Design-Patterns.playground/section-66.swift

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let context = Context()
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(context.isAuthorized, context.userId)
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context.changeStateToAuthorized(userId: "admin")
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(context.isAuthorized, context.userId) // now logged in as "admin"
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context.changeStateToUnauthorized()
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(context.isAuthorized, context.userId)
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let stepCounter = StepCounter()
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stepCounter.totalSteps = 200
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// About to set totalSteps to 200
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// Added 200 steps
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stepCounter.totalSteps = 360
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// About to set totalSteps to 360
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// Added 160 steps
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stepCounter.totalSteps = 896
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// About to set totalSteps to 896
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// Added 536 steps

‎Design-Patterns.playground/section-68.swift

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protocol PrintStrategy {
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func printString(string: String) -> String
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}
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class Printer {
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class Context {
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private var state: State = UnauthorizedState()
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let strategy: PrintStrategy
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func printString(string: String) -> String {
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return self.strategy.printString(string)
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var isAuthorized: Bool {
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get { return state.isAuthorized(self) }
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}
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init(strategy: PrintStrategy) {
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self.strategy = strategy
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var userId: String? {
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get { return state.userId(self) }
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}
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func changeStateToAuthorized(#userId: String) {
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state = AuthorizedState(userId: userId)
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}
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func changeStateToUnauthorized() {
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state = UnauthorizedState()
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}
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}
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class UpperCaseStrategy : PrintStrategy {
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func printString(string:String) -> String {
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return string.uppercaseString
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}
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protocol State {
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func isAuthorized(context: Context) -> Bool
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func userId(context: Context) -> String?
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}
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class LowerCaseStrategy : PrintStrategy {
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func printString(string:String) -> String {
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return string.lowercaseString
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}
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class UnauthorizedState: State {
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func isAuthorized(context: Context) -> Bool { return false }
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func userId(context: Context) -> String? { return nil }
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}
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class AuthorizedState: State {
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let userId: String
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init(userId: String) { self.userId = userId }
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func isAuthorized(context: Context) -> Bool { return true }
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func userId(context: Context) -> String? { return userId }
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}

‎Design-Patterns.playground/section-70.swift

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var lower = Printer(strategy:LowerCaseStrategy())
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lower.printString("O tempora, o mores!")
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var upper = Printer(strategy:UpperCaseStrategy())
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upper.printString("O tempora, o mores!")
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let context = Context()
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(context.isAuthorized, context.userId)
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context.changeStateToAuthorized(userId: "admin")
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(context.isAuthorized, context.userId) // now logged in as "admin"
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context.changeStateToUnauthorized()
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(context.isAuthorized, context.userId)

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