在 Swift 中播放音乐：在展开 Optional 值时意外发现 nil

Question

在做一个项目时，我决定添加一些音乐以在触发某个动作时播放。这是我得到的：

var player : AVAudioPlayer?

几行之后...

func playSound(){
    let alertSound = URL(fileURLWithPath: Bundle.main.path(forResource: "Kalimba", ofType: "wav")!)
    print(alertSound)

    try! AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
    try! AVAudioSession.sharedInstance().setActive(true)

    try! player = AVAudioPlayer(contentsOf: alertSound)
    player!.prepareToPlay()
    player!.play()
}

每当我尝试这个时，触发操作时 xcode 都会向我抛出一个致命错误，说：

线程 1：致命错误：在展开可选值时意外发现 nil

Answer 1

您应该检查您的音乐文件是否附有您的目标？ -

    let path = Bundle.main.path(forResource: "Kalimba", ofType: "wav")
    if path != nil {
        let url = URL(fileURLWithPath: path!)
        print(url)
        let player = AVPlayer(url: url)
        let playerLayer = AVPlayerLayer(player: player)
        playerLayer.frame = self.view.bounds
        self.view.layer.addSublayer(playerLayer)
        player.play()
   } else {
        print("File Not exist")
   }