FactoryMethodパターンでリファクタリングすると、ゲーム開発がどう便利になるのかをSwiftコードで学ぶ：iOS SDKとSwiftで始めるゲーム作成入門（6）（3/4 ページ）

class Char: SKSpriteNode {
    // 省略
    // var power = 1
    var power: Int {
        return 0
    }
    var cost: Int {
        return 10
    }
}
 
class Char1: Char {
    init() {
        super.init(texture: SKTexture(imageNamed: "Char1"), color: UIColor.clearColor(), size: CGSize(width: 32, height: 32))
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
 
    override var power: Int {
        return 1
    }
    override var cost: Int {
        return 10
    }
}
 
class Char2: Char {
    init() {
        super.init(texture: SKTexture(imageNamed: "Char2"), color: UIColor.clearColor(), size: CGSize(width: 32, height: 32))
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
 
    override var power: Int {
        return 2
    }
    override var cost: Int {
        return 20
    }
}
 
class Char3: Char {
    init() {
        super.init(texture: SKTexture(imageNamed: "Char3"), color: UIColor.clearColor(), size: CGSize(width: 32, height: 32))
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    override var power: Int {
        return 3
    }
    override var cost: Int {
        return 30
    }
}

class SetCharScene: SKScene {
    var coin = 100
    var charData = [(name: String, position: CGPoint)]()
 
    // 省略
 
    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
        if touches.count == 1, let point = touches.first?.locationInNode(self) {
            let alert = UIAlertController(title: nil, message: "どのキャラクターを設置しますか?",
                                          preferredStyle: .Alert)
            let rootViewController = UIApplication.sharedApplication().delegate?.window??.rootViewController
            alert.addAction(UIAlertAction(title: "Char1を設置", style: .Default, handler: { _ in
                let char = Char1()
                char.position = point
                self.coin -= char.cost
                self.addChild(char)
                self.charData.append((name: "Char1", position: point))
            }))
            alert.addAction(UIAlertAction(title: "Char2を設置", style: .Default, handler: { _ in
                let char = Char2()
                char.position = point
                self.coin -= char.cost
                self.addChild(char)
                self.charData.append((name: "Char2", position: point))
            }))
            alert.addAction(UIAlertAction(title: "Char3を設置", style: .Default, handler: { _ in
                let char = Char3()
                char.position = point
                self.coin -= char.cost
                self.addChild(char)
                self.charData.append((name: "Char3", position: point))
            }))
            alert.addAction(UIAlertAction(title: "キャンセル", style: .Cancel, handler: nil))
            rootViewController?.presentViewController(alert, animated: true, completion: nil)
        }
    }
}

class GameScene: SKScene, SKPhysicsContactDelegate {
    // 省略
    func createChars(charData: [(name: String, position: CGPoint)]) {
        charData.forEach {
            let char: Char
            if name == "Char1" {
                char = Char1()
            } else if name == "Char2" {
                char = Char2()
            } else {
                char = Char3()
            }
            char.position = $0.position
            char.physicsBody = SKPhysicsBody(rectangleOfSize: char.size)
            char.physicsBody?.contactTestBitMask = 0x1
            addChild(char)
            chars.append(char)
        }
    }
    // 省略
}

class SetCharScene: SKScene {
    // 省略
    override func didMoveToView(view: SKView) {
        // 省略
        let button = Button(text: "ゲーム開始", rect: buttonRect, afterTap: {
            let scene = GameScene(fileNamed: "GameScene")
            scene?.scaleMode = .ResizeFill
            view.presentScene(scene)
            scene?.createChars(self.charData) // ここを修正
        })
        addChild(button)
    }
    // 省略
}