ios - 开始游戏时停止背景音乐

Question

我使用以下代码在 GameViewController.swift 中启动应用程序时启动背景音乐:

class GameViewController: UIViewController {

// VARIABLES
var backgroundMusicPlayer : AVAudioPlayer!

// AUDIO PLAYER
func playBackgroundMusic(filename: String) {
    let url = NSBundle.mainBundle().URLForResource(filename, withExtension: nil)
    var error : NSError? = nil
    do {
        backgroundMusicPlayer = try AVAudioPlayer(contentsOfURL: url!)
    } catch let error1 as NSError {
        error = error1
        backgroundMusicPlayer = nil
    }
    if backgroundMusicPlayer == nil {
        print("Could not create audio player: \(error!)")
        return
    }
    backgroundMusicPlayer.numberOfLoops = -1
    backgroundMusicPlayer.prepareToPlay()
    backgroundMusicPlayer.play()
}

func stopBackgroundMusic() {
    backgroundMusicPlayer.stop()
}

override func viewDidLoad() {
    super.viewDidLoad()
    playBackgroundMusic("MainTheme.mp3")

<< Various irrelevant code >>
}

因为这是在 viewController 中运行的，所以它会通过更改菜单上的场景(即打开“商店”场景)持续存在并创建无缝轨道。当我单击菜单场景上的“播放”按钮时，我希望音乐停止并过渡到游戏。我在 GameViewController 中有 stopBackgroundMusic() 方法，但我不知道如何在菜单场景上调用它。 在菜单场景我尝试了这个:

// TOUCH
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    let touch = touches.first as UITouch?
    let touchLocation = touch!.locationInNode(self)
    let touchedNode = self.nodeAtPoint(touchLocation)
    if touchedNode.name == "startGame" {
        GameViewController.stopBackgroundMusic()
        let transitionType = SKTransition.fadeWithDuration(2)
        let viewSize = self.view?.bounds.size
        let scene = GameScene(size: viewSize!)
        self.view?.presentScene(scene, transition: transitionType)
    }
}

但我收到一条错误消息，说我在调用 stopBackgroundMusic() 时缺少参数 #1，该参数不需要任何参数。我调用这个方法是错误的吗？谢谢!

Answer 1

您使用 GameViewController 引用您的类，但您的函数位于对象实例级别。

如果您在类级别声明变量和函数，则 TouchBegan 函数中的代码应该可以正常工作。

static var backgroundMusicPlayer : AVAudioPlayer!
class func playBackgroundMusic(filename: String) ...
class func stopBackgroundMusic()

override func viewDidLoad() {
   super.viewDidLoad()
   GameViewController.playBackgroundMusic("MainTheme.mp3")

  << Various irrelevant code >>
}