在Swift中播放音樂：意外地發現零，同時展開一個可選值

Question

在一個項目上工作時，我決定添加一些音樂來播放特定動作。下面是我有：

var player : AVAudioPlayer? 

幾行後...

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() 
} 

每當我試試這個，Xcode中拋出我的時候，動作被觸發，說一個致命的錯誤：

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

Answer 1

你應該檢查一下你的音樂文件是否附在你的目標上？ -

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") 
    }