AVPlayer，播放/暂停状态通知？

Question

我正在寻找一种方法来在 AVPlayer 开始播放的确切时刻收到通知。有“rate”属性，但目前我正在使用 NSTimer 定期检查它以获取更新。

我尝试了 KVO，但显然它不符合 KVO 标准。

我知道有事件播放器已结束。但我在这里谈论的是暂停。

我还通过 KVO 订阅了 AVPlayerItem 的“状态”，但它向我显示 HTTP 资源何时完成缓存，没有播放/暂停。我还开始收集所有播放/暂停的调用，然后请求即时 UI 更新，但在 AVPlayer 真正开始播放之前需要更多的运行循环。我只想立即更新我的按钮。

Answer 1

player = AVPlayer(url: URL(fileURLWithPath: path))
player.addObserver(self, forKeyPath: "rate", options: NSKeyValueObservingOptions.new, context: nil)

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
  if keyPath == "rate" {
    if player.rate > 0 {
      print("video started")
    }
  }
}

迅速

Answer 2

将观察者添加到 AVPlayer 对象的 rate 值：

player.addObserver(self, forKeyPath: "rate", options: [], context: nil)

并覆盖 rate 更改时调用的方法：

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "rate", let player = object as? AVPlayer {
        if player.rate == 1 {
            print("Playing")
        } else {
            print("Paused")
        }
    }
}

Answer 3

需要向 AVPlayer 对象的 rate 值添加观察者：

player?.addObserver(self, forKeyPath: "rate", options: NSKeyValueObservingOptions.new, context: nil)

重写以下方法以观察 rate 属性的变化

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "rate" {
        if let status = player?.timeControlStatus {
            switch status{
            case .paused:
                //Paused mode
                print("paused")
            case .waitingToPlayAtSpecifiedRate:
                //Resumed
                print("resumed")
            case .playing:
                //Video Ended
                print("ended")
            @unknown default:
                print("For future versions")
            }
        }
    }
}

Answer 4

为什么说“率”不是KVO的抱怨呢？
这对我有用。

这就是我所做的：

- (void)viewDidLoad
{
    ...

    [self.player addObserver:self forKeyPath:@"rate" options:0 context:nil];
}

然后：

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if ([keyPath isEqualToString:@"rate"]) {
    if ([self.player rate]) {
        [self changeToPause];  // This changes the button to Pause
    }
    else {
        [self changeToPlay];   // This changes the button to Play
    }
}
}

Answer 5

对于 iOS 10 及以上版本，您可以检查 AVPlayer timeControlStatus 的新属性。

if(avPlayerObject.timeControlStatus==AVPlayerTimeControlStatusPaused)
{
//Paused mode
}
else if(avPlayerObject.timeControlStatus==AVPlayerTimeControlStatusPlaying)
{
 //Play mode
}

Answer 6

AVPalyer 作为默认观察者来跟踪视频的当前持续时间，当您暂停或恢复视频时，您可以通过使用一个全局变量来获取暂停时间（观察者内部更新该变量）

CMTime interval = CMTimeMake(1, 1);

//The capture of self here is coming in with your implicit property access of self.currentduration - you can't refer to self or properties on self from within a block that will be strongly retained by self.

//You can get around this by creating a weak reference to self before accessing timerDisp inside your block
__weak typeof(self) weakSelf = self;

self.timeObserverToken = [_player addPeriodicTimeObserverForInterval:interval queue:NULL usingBlock: ^(CMTime time)
{
    _currentDuration = (int)CMTimeGetSeconds (_player.currentTime);

    if(!_isPlaying)
    {
        _pausedDuration = _currentDuration;
    }
}

Answer 7

如果您的目标是 iOS 13 及更高版本，则可以使用 Combine 优雅地实现此目的：

cancellable = myAVPlayerInstance.publisher(for: \.timeControlStatus)
    .sink { [unowned self] status in
       ...
    }

其中 status 是 AVPlayer 的任何 case .TimeControlStatus