如何在 Swift Playground 中完成歌曲时调用函数

Question

我正在尝试在 Swift 操场上播放完歌曲时调用一个函数。这是我正在使用的代码：

NotificationCenter.default.addObserver(self, selector: Selector(("playerDidFinishPlaying:")), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: winMusic)

但是当歌曲播放完毕时，该函数没有被调用，我不知道为什么？这显然与 iOS 应用中的不同。

var winMusic = NSURL(fileURLWithPath: Bundle.main.path(forResource: "win", ofType: "mp3")!)
var winPlayer: AVAudioPlayer? = nil
class Responder : NSObject {
    func playerDidFinishPlaying() {
        print("test")
        /* Nothing printed here */
    }
    func action(sender: UIButton) {
        NotificationCenter.default.addObserver(self, selector: #selector(Responder.playerDidFinishPlaying), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: winMusic)
        NotificationCenter.default.post(name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: nil)
        winPlayer!.play()
    }
}

Answer 1

AVAudioPlayer 不会发布 AVPlayerItemDidPlayToEndTime 通知。你需要给玩家一个委托。见https://developer.apple.com/reference/avfoundation/avaudioplayerdelegate/1389160-audioplayerdidfinishplaying

Answer 2

将您的 winPlayer 委托设置为，

winPlayer?.delegate = self

并实现方法

func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
    if flag == true {
        // song finished successfully here
    }
}

代表的位置由您决定。