MPRemoteCommandCenter的removeTarget仅在第一次时不起作用

Question

我正在通过两个viewController显示MPRemoteCommandCenter。

1. MediaViewController
2. DownloadViewController

我正在处理播放，暂停，下一个，上一个动作以及在单个视图控制器中注册目标。

extension MediaViewController {

// Call in viewDidload
func setupNowPlayingInfoCenter() {
    try! AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
    try! AVAudioSession.sharedInstance().setActive(true)
    deinitNowPlayInfoCenter()
    MPRemoteCommandCenter.shared().playCommand.addTarget(self, action: #selector(self.playPressed))
    MPRemoteCommandCenter.shared().pauseCommand.addTarget(self, action: #selector(self.pausePressed))
    MPRemoteCommandCenter.shared().nextTrackCommand.addTarget(self, action: #selector(self.nextPressed))
    MPRemoteCommandCenter.shared().previousTrackCommand.addTarget(self, action: #selector(self.previousPressed))
    MPRemoteCommandCenter.shared().skipForwardCommand.isEnabled = false
    MPRemoteCommandCenter.shared().skipBackwardCommand.isEnabled = false
}

//Call this method when move to DownloadViewController.
func deinitNowPlayInfoCenter() {
    MPRemoteCommandCenter.shared().playCommand.removeTarget(self)
    MPRemoteCommandCenter.shared().pauseCommand.removeTarget(self)
    MPRemoteCommandCenter.shared().nextTrackCommand.removeTarget(self)
    MPRemoteCommandCenter.shared().previousTrackCommand.removeTarget(self)
}

private func updateNowPlayingInfoCenter(reset: Bool = false) {

    if reset {
        MPNowPlayingInfoCenter.default().nowPlayingInfo = [:]
        return
    }

    let mediaModal: MediaModel
    if arrMedia.count > currentIndex, let player = self.playerViewController?.player {
        mediaModal = arrMedia[currentIndex]
        let nowPlayingInfo = [MPMediaItemPropertyTitle: mediaModal.media_title ?? "",
                              MPMediaItemPropertyAlbumTitle: mediaModal.event_type.name,
                              MPMediaItemPropertyArtist: mediaModal.mediaType ?? "",
                              MPNowPlayingInfoPropertyElapsedPlaybackTime: CMTimeGetSeconds(player.currentTime())
                              ] as [String : Any]

        MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
    }
}
}

与DownloadViewController相同

extension DownloadViewController {

//call in viewdidload.
func setupNowPlayingInfoCenter() {
    try! AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
    try! AVAudioSession.sharedInstance().setActive(true)
    UIApplication.shared.endReceivingRemoteControlEvents()
    UIApplication.shared.beginReceivingRemoteControlEvents()

    self.deinitNowPlayInfoCenter()
    MPRemoteCommandCenter.shared().playCommand.addTarget(self, action: #selector(playPressed))
    MPRemoteCommandCenter.shared().pauseCommand.addTarget(self, action: #selector(pausePressed))
    MPRemoteCommandCenter.shared().nextTrackCommand.addTarget(self, action: #selector(nextPressed))
    MPRemoteCommandCenter.shared().previousTrackCommand.addTarget(self, action: #selector(previousPressed)) 
    MPRemoteCommandCenter.shared().skipForwardCommand.isEnabled = false
    MPRemoteCommandCenter.shared().skipBackwardCommand.isEnabled = false
}

//call in viewWillDisappear
func deinitNowPlayInfoCenter() { 
    MPRemoteCommandCenter.shared().playCommand.removeTarget(self)
    MPRemoteCommandCenter.shared().pauseCommand.removeTarget(self)
    MPRemoteCommandCenter.shared().nextTrackCommand.removeTarget(self)
    MPRemoteCommandCenter.shared().previousTrackCommand.removeTarget(self)
}

private func updateNowPlayingInfoCenter(reset: Bool = false) {

    if reset {
        MPNowPlayingInfoCenter.default().nowPlayingInfo = [:]
        return
    }

    let mediaModal: MediaModel
    if arrMedia.count > currentIndex, let player = self.playerViewController?.player {
        mediaModal = arrMedia[currentIndex]
        let nowPlayingInfo = [MPMediaItemPropertyTitle: mediaModal.media_title ?? "",
                              MPMediaItemPropertyAlbumTitle: mediaModal.event_type.name,
                              MPMediaItemPropertyArtist: mediaModal.mediaType ?? "",
                              MPNowPlayingInfoPropertyElapsedPlaybackTime: CMTimeGetSeconds(player.currentTime())
                              ] as [String : Any]

        MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
    }
}
}

我正在处理受尊重的视图控制器（MPRemoteCommandCenter通过其打开）中的操作。

除一个测试用例外，一切正常

第一次登录时，直接移至我的MediaViewController（在TabBarViewController中选择Media TabItem）并打开downloadViewController（从MediaViewController导航栏中的BarButtonItem）并播放歌曲（AvPlayerViewController），然后单击{{1}中的暂停按钮}。 MediaViewController的目标而不是DownloadViewController的目标被调用。我只在这个测试案例中发生。除了这种情况，它工作正常。如果用户注销并再次登录，它将再次生成。

如果用户登录并且比等待一段时间（30秒）或执行其他操作再多做一件事，那么它可以正常工作，但是如果用户直接进入mediaviewcontroller而没有花费一秒钟，那么它就会发生。

它仅在第一次发生。当用户登录后比一切正常。我认为

MPRemoteCommandCenter

开始加载应用程序时，

不起作用。