使用AVPlayer实现背景音乐播放，同时在VLCMediaPlayer的代理方法中添加对AVPlayer状态的监听，根据AVPlayer播放状态控制背景音乐的播放和暂停。

示例代码：

//创建AVPlayer实例
let audioUrl = URL(fileURLWithPath: Bundle.main.path(forResource: "audio", ofType: "mp3")!)
let audioPlayer = AVPlayer(url: audioUrl)

//添加AVPlayer状态监听
audioPlayer.addObserver(self, forKeyPath: "timeControlStatus", options: [.new, .old], context: nil)

//VLCMediaPlayer代理方法中控制背景音乐播放和暂停
func mediaPlayerStateChanged(_ aNotification: Notification!) {
  if let mediaPlayer = mediaPlayer {
    switch mediaPlayer.state {
    case .stopped, .ended, .error:
      audioPlayer.pause()
    case .playing:
      audioPlayer.play()
    case .paused:
      break
    default:
      break
    }
  }
}

//AVPlayer状态监听方法中根据播放状态控制背景音乐播放和暂停
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
  if let player = object as? AVPlayer,
  keyPath == "timeControlStatus",
  let statusInt = change?[NSKeyValueChangeKey.newKey] as? Int,
  let status = AVPlayer.TimeControlStatus(rawValue: statusInt) {
    switch status {
    case .paused:
      audioPlayer.pause()
    case .playing:
      audioPlayer.play()
    default:
      break
    }
  }
}