如何在场景之间转换时保持声音关闭

Question

我在Sprite Kit中创建了这个游戏，我让用户能够通过按下按钮来静音，然后才能点击并启动游戏。然而，当游戏结束并且GameOverScene出现时，音乐仍然保持静音。当一个新的GameScene被调用时，音乐会再次开始播放。任何人都知道如何解决这个问题。这是我的音乐代码。

var backgroundMusicPlayer: AVAudioPlayer!

func playBackgroundMusic(filename: String) {
let url = NSBundle.mainBundle().URLForResource(
    filename, withExtension: nil)
if (url == nil) {
    println("Could not find file: \(filename)")
    return
}

var error: NSError? = nil
backgroundMusicPlayer =
    AVAudioPlayer(contentsOfURL: url, error: &error)
if backgroundMusicPlayer == nil {
    println("Could not create audio player: \(error!)")
    return
}

backgroundMusicPlayer.numberOfLoops = -1
backgroundMusicPlayer.prepareToPlay()
backgroundMusicPlayer.play()
}



override func didMoveToView(view: SKView) {

    muteSound.name = "muteSound"
    muteSound.position.x = view.center.x
    muteSound.position.y = view.center.y + 100
    self.addChild(muteSound)

    playBackgroundMusic("Box Office.mp3")

}


override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)
        let node = self.nodeAtPoint(location)

        if node.name == "muteSound" {
            backgroundMusicPlayer.stop()
        }
}