デザインパターン「ファーストクラスコレクション」でSwiftコードの保守性・可読性を上げる方法をゲームのコードから学ぶ：iOS SDKとSwiftで始めるゲーム作成入門（4）（2/2 ページ）

class GameScene: SKScene, SKPhysicsContactDelegate {
    enum State {
        case Playing
        case GameClear
        case GameOver
    }
    var state = State.Playing
    var enemies = [SKSpriteNode]()
    let char = SKSpriteNode(imageNamed: "Char")
    var routes = [float2]()
 
    override func didMoveToView(view: SKView) {
        // 省略
 
        routes = routesWithField(field)
 
        // 敵を10体出現させる処理
        (0...10).forEach {
            performSelector("createEnemy", withObject: nil, afterDelay: Double($0))
        }
    }
 
    func createEnemy() {
        guard let view = view else {
            return
        }
 
        let enemy = SKSpriteNode(imageNamed: "Enemy")
        var routes = self.routes
        var prevPosition = routes.removeFirst()
        let actions = routes.map { p -> SKAction in
            let dx = p.x - prevPosition.x
            let dy = p.y - prevPosition.y
            let duration = Double(sqrt(dx * dx + dy * dy) / 100)
            prevPosition = p
            return SKAction.moveTo(CGPoint(x: Double(p.x), y: Double(p.y)), duration: duration)
        }
 
        let fieldImageLength = view.frame.width / 10
        enemy.name = "enemy"
        enemy.position = CGPoint(x: fieldImageLength * 2, y: view.frame.height)
        enemy.physicsBody = SKPhysicsBody(rectangleOfSize: enemy.size)
        enemy.runAction(SKAction.sequence(actions)) {
            self.state = .GameOver
 
            let myLabel = SKLabelNode(fontNamed: "HiraginoSans-W6")
            myLabel.text = "ゲームオーバー"
            myLabel.fontSize = 45
            myLabel.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) - 20)
            self.addChild(myLabel)
        }
        addChild(enemy)
 
        enemies.append(enemy)
    }
 
    func didBeginContact(contact: SKPhysicsContact) {
        [contact.bodyA, contact.bodyB].forEach {
            if $0.node?.name == "enemy" {
                $0.node?.removeFromParent()
                $0.node?.removeAllActions()
            }
        }
 
        if enemies.filter({ $0.parent != nil }).count == 0 {
            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)
        }
    }
 
    // 省略
}

import UIKit
import SpriteKit
 
class EnemyList {
    private var enemies = [SKSpriteNode]()
 
    func appendEnemy(enemy: SKSpriteNode) {
        enemies.append(enemy)
    }
 
    func isAllEnemyRemoved() -> Bool {
        return enemies.filter { $0.parent != nil }.count == 0
    }
}

class GameScene: SKScene, SKPhysicsContactDelegate {
    // 省略
    // var enemies = [SKSpriteNode]()
    var enemyList = EnemyList()
    // 省略
 
    func createEnemy() {
        // 省略
        // enemies.append(enemy)
        enemyList.appendEnemy(enemy)
    }
 
    func didBeginContact(contact: SKPhysicsContact) {
        // 省略
        // if enemies.filter({ $0.parent != nil }).count == 0 {
        if enemyList.isAllEnemyRemoved() {
            // 省略
        }
    }
    // 省略
}