无法观察AVPlayerItem的@“status”键 [英] Can’t observe AVPlayerItem for @“status” key

问题描述

我正在尝试从网址播放流，但这是一个问题。 ObserveValueForKeyPath：ofObject：更改：上下文不执行。据我了解，这不取决于streamURL，它是否正确。它必须从AVPlayerItemStatusUnknown将状态更改为AVPlayerItemStatusReadyToPlay或AVPlayerItemStatusFailed。但是，我在浏览器中检查了该URL，它运行正常。所以有什么问题？我观看了WWDC视频，它说，如果你有音频流，请在 AVAsset之前使用AVPLayerItem 。

I’m trying to play stream from URL, but here is an issue. ObserveValueForKeyPath:ofObject:change:context just doesn’t execute. As I understand, it is not depends on streamURL, nether it is correct or not. It must change status to AVPlayerItemStatusReadyToPlay or AVPlayerItemStatusFailed from AVPlayerItemStatusUnknown. But nonetheless I checked that URL in browser, and it is working fine. So, what’s the problem? I watched WWDC video about it, and it says, if you have audio stream, use AVPLayerItem before AVAsset.

这是我的代码：

- (void) prepare
{
    NSURL * trackStreamURL = [NSURL URLWithString:streamURL];
    NSLog(@"STREAM URL: %@",trackStreamURL);
    _playerItem = [AVPlayerItem playerItemWithURL:trackStreamURL];
    [_playerItem addObserver:self forKeyPath:@"status" options:0 context:nil];
}
- (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    NSLog(@"KEY PATH    : %@", keyPath);
    NSLog(@"CHANGE      : %@", change);
}

提前致谢！

推荐答案

我一直在 AVPlayer 上观察到状态属性而不是 AVPlayerItem 因为你需要一个玩家来玩玩家物品。事实上，我甚至从未查看过玩家项目的状态属性。

I've always observed the status property on the AVPlayer instead of the AVPlayerItem since you need a player to play the player item anyway. In fact, I had never even looked at the status property of the player item.

玩家项目的状态可能永远不会改变，因为没有玩家准备好播放。因此，使用玩家项目创建一个玩家并观察玩家的状态（或者可能，仍然是玩家项目的状态）。

The status of the player item probably never changes because there is no player that is ready to play it. So, Create a player with the player item and observe the status of the player (or possibly, still the status of the player item).

AVPlayer *player = [AVPlayer playerWithPlayerItem:playerItem];

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