如何监控AVAudioPlayerNode完成播放

Question

哦，嘿！我一直在努力弄清楚如何让我的AVAudioPlayerNode()在到达SwiftUI项目中的文件末尾时自动停止播放。正如您在下面看到的，我的音频文件不是通过AVAudioEngine，而是AVAudioPlayer有一个audioPlayerDidFinishPlaying函数，这很好。但是，对于使用play函数遍历引擎的音频文件，没有类似的内容，我也不知道如何使它的行为类似。

我试过建造这样的东西

    func audioPlayerDidFinishPlaying2(_ player: AVAudioPlayerNode, successfully flag: Bool) {
        if flag {
            isPlaying = false
            print("Playback Engine Stopped")
        }
    }

但这看上去什么都没做。

通过调用stopPlayback2()手动停止引擎的回放很好。

我打电话给引擎播放器

do {
    try self.audioPlayer.play(self.audioURL)
  }
    catch let error as NSError {
      print(error.localizedDescription)
  }

我看过其他的，所以这里和这里的帖子，但这两个解决方案都不适合我。如果您有任何建议，我将非常感谢您的意见！谢谢！！

AudioPlayer.swift

class AudioPlayer: NSObject, ObservableObject, AVAudioPlayerDelegate {
    
    let objectWillChange = PassthroughSubject<AudioPlayer, Never>()
    var isPlaying = false {
        didSet {
            objectWillChange.send(self)
        }
    }

    
    var audioPlayer: AVAudioPlayer!
    
    func startPlayback (audio: URL) {

        let playbackSession = AVAudioSession.sharedInstance()
        
        do {
            try playbackSession.overrideOutputAudioPort(AVAudioSession.PortOverride.speaker)
        } catch {
            print("Playing over the device's speakers failed")
        }
        do {
            audioPlayer = try AVAudioPlayer(contentsOf: audio)
            audioPlayer.delegate = self
            audioPlayer.play()
            isPlaying = true
        } catch {
            print("Playback failed.")
        }
    }
    
    func stopPlayback() {
        
        audioPlayer.stop()
        isPlaying = false
        
    }
    
    func stopPlayback2() {
        engine.stop()
        isPlaying = false
    }
    
    func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
        if flag {
            isPlaying = false
            print("Playback Stopped")
        }
    }

    let engine = AVAudioEngine()
    let speedControl = AVAudioUnitVarispeed()
    let pitchControl = AVAudioUnitTimePitch()
    
    func play(_ url: URL) throws {
        let file = try! AVAudioFile(forReading: url)

        let avPlayer = AVAudioPlayerNode()

        engine.attach(avPlayer)
        engine.attach(pitchControl)
        engine.attach(speedControl)

        engine.connect(avPlayer, to: speedControl, format: nil)
        engine.connect(speedControl, to: pitchControl, format: nil)
        engine.connect(pitchControl, to: engine.mainMixerNode, format: nil)

        avPlayer.scheduleFile(file, at: nil)

        isPlaying = true
        try engine.start()
        avPlayer.play()
    }
    ```


  [1]: https://stackoverflow.com/questions/34238432/avaudioengine-avaudioplayernode-didfinish-method-like-avaudioplayer
  [2]: https://stackoverflow.com/questions/59080708/calling-stop-on-avaudioplayernode-after-finished-playing-causes-crash

Answer 1

与其使用avPlayer.scheduleFile(file, at: nil)，不如使用带有完成处理程序的方法的形式：

avPlayer.scheduleFile(file, at: nil) {
    //call your completion function here
    print("Done playing")
}