ios - 使用 MPRemoteCommandCenter 时未调用播放/暂停回调

Question

我正在构建一个音乐播放器应用，一切正常。到目前为止，我一直在使用系统音乐播放器，但现在想改用应用程序音乐播放器，这就是我遇到问题的地方——我这辈子都不知道如何获得我的音乐播放器从 iOS 控制中心调用播放/暂停回调。这是我在主视图 Controller 中使用的代码:

override func viewDidLoad() {
    super.viewDidLoad()

    self.musicPlayer = MPMusicPlayerController.applicationMusicPlayer()

    self.registerForMediaPlayerNotifications()
    UIApplication.sharedApplication().beginReceivingRemoteControlEvents()

    let commandCenter = MPRemoteCommandCenter.sharedCommandCenter()

    commandCenter.previousTrackCommand.enabled = false
    commandCenter.previousTrackCommand.addTarget(self, action: "previousTrack")
    commandCenter.nextTrackCommand.enabled = false
    commandCenter.nextTrackCommand.addTarget(self, action: "nextTrack")
    commandCenter.togglePlayPauseCommand.enabled = true
    commandCenter.togglePlayPauseCommand.addTarget(self, action: "playOrPauseMusic")
    commandCenter.pauseCommand.addTarget(self, action: "playOrPauseMusic")
    commandCenter.pauseCommand.enabled = true
    commandCenter.playCommand.addTarget(self, action: "playOrPauseMusic")
    commandCenter.playCommand.enabled = true

    [...]
}


func previousTrack() {
}

func nextTrack() {
}

func playOrPauseMusic() {
   print("playOrPause")
}

Answer 1

我遇到了同样的问题并注意到 togglePlayPauseCommand 的回调没有被调用，但是 previousTrackCommand 被调用了。因此，经过一些实验后，我通过删除 togglePlayPauseCommand 并单独实现 playCommand 和 pauseCommand 的内联回调来实现此功能 - 请注意使用自定义选择器不起作用，它们必须是内联回调。

let commandCenter = MPRemoteCommandCenter.shared()

commandCenter.playCommand.addTarget { (commandEvent) -> MPRemoteCommandHandlerStatus in
    moviePlayer.prepareToPlay()
    moviePlayer.play()
    return MPRemoteCommandHandlerStatus.success
}

commandCenter.pauseCommand.addTarget { (commandEvent) -> MPRemoteCommandHandlerStatus in
    moviePlayer.pause()
    return MPRemoteCommandHandlerStatus.success
}