MPNowPlayingInfoCenter没有显示细节

Question

今天，我花了几个小时试图找出为什么MPNowPlayingInfoCenter没有工作，但没有成功。我要它显示信息在控制中心和锁定屏幕，媒体是一个视频。

以下是问题所在：

我有一个名为GlobalAVPlayer的单例类，它包含一个AVPlayerViewController。它是一个单例，因为必须只有一个，而我需要在全球访问它。

class GlobalAVPlayer: NSObject {
static let sharedInstance = GlobalAVPlayer()

private var _currentVideo: Video?

var playerViewController = AVPlayerViewController()

var isPlaying: Bool = false
var almostPlaying: Bool = false
var hasItemToPlay: Bool = false

var currentVideo: Video?
{
    set {
        _currentVideo = newValue
        notify_VideoChanged()
    }
    get {
        return _currentVideo
    }
}

private var player: AVPlayer!

override init()
{
    super.init()
    player = AVPlayer()
    playerViewController.player = player
    
    player.addObserver(self, forKeyPath: "rate", options: NSKeyValueObservingOptions.New, context: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(didPlayToEnd), name: "AVPlayerItemDidPlayToEndTimeNotification", object: nil)
    
}

func itemToPlay(item: AVPlayerItem)
{
    if let player = player {
        almostPlaying = true
        hasItemToPlay = true
        player.replaceCurrentItemWithPlayerItem(item)
    }
}

func didPlayToEnd()
{
    print("[GlobalAVPlayer] End video notification")
    let time = CMTimeMakeWithSeconds(0, 1)
    player.seekToTime(time)
}
func play()
{
    if player.rate == 0
    {
        player.play()
        if player.rate != 0 && player.error == nil
        {
            isPlaying = true
            print("[GlobalAVPlayer] Playing video without errors")
        }
    }
}

func pause()
{
    if player.rate == 1
    {
        player.pause()
        if player.rate == 0 && player.error == nil
        {
            isPlaying = false
            print("[GlobalAVPlayer] Pausing video without errors")
        }
    }
}

func notify_PlaybackChanged()
{
    NSNotificationCenter.defaultCenter().postNotificationName("globalAVPlayerPlaybackChanged", object: self)
}

func notify_VideoChanged()
{
    NSNotificationCenter.defaultCenter().postNotificationName("globalAVPlayerVideoChanged", object: self)
}

override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
    if keyPath == "rate" {
        let newRate = change!["new"] as! Int
        //rate = 0 (il player è fermo)      rate = 1 (il player sta andando)
        self.isPlaying = newRate == 1 ? true : false
        notify_PlaybackChanged()
    }
}

deinit
{
    player.removeObserver(self, forKeyPath: "rate", context: nil)
}
}

当应用程序启动时，init被称为init，之后，我使用"itemToPlay“方法来更改视频。我还正确地(我认为)在AppDelegate中配置了音频会话：

do
    {
        let session = AVAudioSession.sharedInstance()
        try session.setCategory(AVAudioSessionCategoryPlayback)
        try session.setActive(true)
    }
    catch
    {
        print("[AppDelegate] Something went wrong")
    }

我试着把MPNowPlayingInfoCenter.defaultCenter().nowPlayingInfo = something放在任何地方，但是当我把它放到play()方法中时，我可以在控制中心看到1秒的视频标题。在那之后，它消失了，播放控件变成了灰色。信息是正确存储的，因为当我将nowPlayingInfo内容打印到控制台时，一切都如期而至。我尝试在不同的地方使用becomeFirstResponder和UIApplication.beginReceivingRemoteControlEvents，但都没有成功。

谢谢

Answer 1

从updatesNowPlayingInfoCenter，10开始，AVPlayerViewController中有一个名为BOOL的属性，该属性具有默认值：YES。只需将其改为NO

//playerController is an instance of AVPlayerViewController
if ([self.playerController respondsToSelector:@selector(setUpdatesNowPlayingInfoCenter:)])
{
    self.playerController.updatesNowPlayingInfoCenter = NO;
}