ゲームのState管理を簡単にするiOS 9 GameplayKitのクラスとは：iOS SDKとSwiftで始めるゲーム作成入門（5）（4/4 ページ）

class Char: SKSpriteNode {
    // stateMachineプロパティーがstateを保持する
    lazy var stateMachine: GKStateMachine = {
        let stateMachine = GKStateMachine(states: [
            AttackState(char: self),
            StayState(char: self)
            ])
        stateMachine.enterState(AttackState)
        return stateMachine
    }()
 
    // GKStateMachineが保持できるようにCharStateはGKStateのサブクラスにする
    class CharState: GKState {
        weak var char: Char?
        var power: Int {
            return char?.power ?? 0
        }
 
        init(char: Char?) {
            self.char = char
        }
 
        func enableToAttack() -> Bool {
            return false
        }
    }
 
    class AttackState: CharState {
        override func enableToAttack() -> Bool {
            return true
        }
    }
 
    class AngryState: CharState {
        var enteredDate = NSDate()
        override var power: Int {
            return char?.power ?? 0
        }
 
        override func enableToAttack() -> Bool {
            return true
        }
 
        override func didEnterWithPreviousState(previousState: GKState?) {
            enteredDate = NSDate()
        }
 
        override func updateWithDeltaTime(seconds: NSTimeInterval) {
            if NSDate().timeIntervalSinceDate(enteredDate) > 10 {
                // stateの変更はenterStateメソッドを利用する
                char?.stateMachine.enterState(AttackState)
            }
        }
    }
 
    class StayState: CharState {
        var enteredDate = NSDate()
        override func didEnterWithPreviousState(previousState: GKState?) {
            enteredDate = NSDate()
        }
 
        override func updateWithDeltaTime(seconds: NSTimeInterval) {
            if NSDate().timeIntervalSinceDate(enteredDate) > 0.2 {
                char?.stateMachine.enterState(AttackState)
            }
        }
 
        override func enableToAttack() -> Bool {
            return false
        }
    }
    var power = 1
}

class GameScene: SKScene, SKPhysicsContactDelegate {
    // 略...
    override func update(currentTime: NSTimeInterval) {
        char.stateMachine.updateWithDeltaTime(currentTime)
        if let charState = char.stateMachine.currentState as? Char.CharState where charState.enableToAttack() {
            enemyList.enemiesCloseToPoint(char.frame.origin, distance: 50).forEach {
                $0.life -= charState.power
                char.stateMachine.enterState(Char.StayState.self)
                if $0.life <= 0 {
                    $0.physicsBody?.node?.removeFromParent()
                    $0.physicsBody?.node?.removeAllActions()
 
                    if enemyList.isAllEnemyRemoved() {
                        state = .GameClear
 
                        let myLabel = SKLabelNode(fontNamed: "HiraginoSans-W6")
                        myLabel.text = "ゲームクリア"
                        myLabel.fontSize = 45
                        myLabel.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) - 20)
                        addChild(myLabel)
                    }
                }
            }
        }
    }
    // 略...
}