Sprite Kit场景切换Xcode 7

Question

我正在尝试从GameScene到Title场景进行简单的场景切换，但我一直收到错误：＆＃34;线程1：EXC_BAD_INSTRUCTION（代码= EXC_1386_INVOP，子代码= 0x0）＆＃34;在线上                  skView.presentScene（titleScene !, transition：transition）

我该如何解决这个问题？

import SpriteKit

let playButton = SKSpriteNode(imageNamed: "Spaceship")

class GameScene: SKScene {
override func didMoveToView(view: SKView) {
    playButton.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMaxY(self.frame))
    self.addChild(playButton)
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {


    for touch in touches {
        let location = touch.locationInNode(self)


        if playButton.containsPoint(location) {
            let titleScene = TitleScene(fileNamed: "TitleScene")
            let transition = SKTransition.fadeWithDuration(0.5)
            let skView = self.view as SKView!
            skView.ignoresSiblingOrder = true
            titleScene?.scaleMode = .AspectFill
            skView.presentScene(titleScene!, transition: transition)


        }
    }


}

}