Question

我正在尝试构建音乐应用。音乐播放完美，但音乐结束后不播放下一首歌。我正在寻找这个解决方案。当我尝试一些解决方案是给我错误。

由于未捕获的异常'NSInvalidArgumentException'而导致应用程序停止，理由：' - [Shironamhin.MusicPlayer playerDidFinishPlaying：]：无法识别的选择器发送到实例0x17003d960

我正在尝试这种方式

class MusicPlayer: NSObject {

    static let player = MusicPlayer()

    //this is global variable
    var player : AVPlayer?
    var playerItem:AVPlayerItem?

    func initPlayer(){
        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
            try AVAudioSession.sharedInstance().overrideOutputAudioPort(AVAudioSessionPortOverride.speaker)
            print("AVAudioSession Category Playback OK")
            do {
                try AVAudioSession.sharedInstance().setActive(true)

                print("AVAudioSession is Active")

            } catch let error as NSError {
                print(error.localizedDescription)
            }
        } catch let error as NSError {
            print(error.localizedDescription)
        }
}
    func playMusic(_ musicUrl: String?) {
        if let mm = musicUrl {
            var url: URL!
            url = URL(string: mm)
            playerItem = AVPlayerItem(url: url)
            player = AVPlayer(playerItem: playerItem)
            player?.volume = 1.0
            player?.rate = 1.0
            player?.play()
            NotificationCenter.default.addObserver(self, selector: Selector(("playerDidFinishPlaying:")), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: playerItem)


        }

        func playerDidFinishPlaying(note: NSNotification) {

            print("call")

        }
    }




}

另外我如何实现这个playerDidFinishPlaying ??

Answer 1

自Swift 3起，您必须声明Selectors，如下所示：#selector(playerDidFinishPlaying(email:))自Swift 4起，您必须将@objc属性添加到该函数中：

@objc func audioDidFinishPlaying(note: NSNotification) {
    print("call")
}

顺便说一句，AVAudioPlayerDelegate有一个很好的功能：optional func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool)，它可能更容易使用它。：）

Answer 2

我同意@ user6603599，这就是我使用的。

func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
    print("\naudioPlayerDidFinishPlaying")
}

确保您的MusicPlayer类设置如下：

类MusicPlayer：AVAudioPlayerDelegate {

在iOS swift完成音乐播放音乐时播放下一首歌曲

2 个答案: