如何从MPNowPlayingInfoCenter访问ViewController

Question

我正在开发一个音频播放器，并遇到了这种情况:我有一个TrackDetailView，当我单击TableView单元格时，它会打开并播放曲目。此外，我还实现了后台播放和MPNowPlayingInfoCenter。当我在MPNowPlayingInfoCenter中按下暂停或播放按钮时，我希望我的TrackDetailView上的按钮图像也会改变，但我就是做不到。如果有任何帮助，我将很高兴。重要说明(！)TrackDetailView和MPNowPlayingInfoCenter在不同的类中。当我将它们放在一个类中时，一切都可以正常工作。我的代码：

class TrackDetailView: UIView {
   var audioPlayer = AudioPlayer()
   ...
   @IBOutlet var playPauseButton: UIButton!
   ...
   //Loading with view
   func set() {
   setupMediaPlayerNotificationView()
   }
}

class AudioPlayer {
var trackDetailView: TrackDetailView?
func setupMediaPlayerNotificationView() {
        let commandCenter = MPRemoteCommandCenter.shared()
        
        commandCenter.playCommand.addTarget { [unowned self] event in
            if self.player.rate == 0.0 {
                self.player.play()
                self.trackDetailView?.playPauseButton.setImage(#imageLiteral(resourceName: "pause"), for: .normal)
            }
            return .commandFailed
        }
        
        commandCenter.pauseCommand.addTarget { [unowned self] event in
            if self.player.rate == 1.0 {
                self.player.pause()
                self.trackDetailView?.playPauseButton.setImage(#imageLiteral(resourceName: "play"), for: .normal)
                return .success
            }
            return .commandFailed
        }
       ...
    }
}

我想我在TrackDetailView类的一个实例上遇到了问题。

Answer 1

对于此实例，您需要确保

var audioPlayer = AudioPlayer()

你设置

audioPlayer.trackDetailView = self

e.x在这里

func set() {
  audioPlayer.trackDetailView = self
  audioPlayer.setupMediaPlayerNotificationView()
}