iOS AVPlayerViewController不显示播放控件

Question

知道为什么我可以让我的AVPlayerViewController类播放内容,但无法让它显示播放控件吗？播放器按预期加载内容,但就是这样.

在我的MediaPlayerViewController.m类中,我有:

#pragma mark - Player
- (void)setupPlayer{

    // Sample URLs to use either a local file or streaming URL
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"Besan" withExtension:@"mp4"];
    //url = [NSURL URLWithString:@"http://www.youtube.com/watch?v=qcI2_v7Vj2U"];

    // Create an instance of the AVPlayer object
    self.player = [AVPlayer playerWithURL:url];


    // Keep an eye on the status of our player
    [self.player addObserver:self forKeyPath:@"status" options:0 context:nil];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{

    if (object == self.player && [keyPath isEqualToString:@"status"]) {
        if (self.player.status == AVPlayerStatusFailed){
            NSLog(@"AVPlayer setup failed");
        } else if (self.player.status == AVPlayerStatusReadyToPlay) {
            NSLog(@"AVPlayer is ready to play");
            [self.player play];
        }
    }
}

Answer 1

它不是框架错误,而是与键值观察的工作方式有关.通过实施

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

在您的ViewController中,您将覆盖AVPlayerViewController的实现.解决方案是在注册观察者时添加上下文:

static NSString* const AVPlayerStatusObservationContext = @"AVPlayerStatusObservationContext";

然后像这样注册你的观察者

[self.player addObserver:self forKeyPath:@"status" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionPrior context:(__bridge void *)(AVPlayerStatusObservationContext)];

并在observeValueForKeyPath中执行以下操作

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{

    if (context == (__bridge void *)(AVPlayerStatusObservationContext))
    {
        NSLog(@"Change Object %@, Value %@",object,change);
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

Answer 2

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context 正如我在对问题的评论中指出的那样，当您在 AVPlayerViewController 中实现时，控件会消失。它可以是一个空的实现；播放器控件不会出现。这一定是一个框架错误，我很震惊（震惊！）苹果没有发现这一点。

我的解决方案是在不同的类中实现观察者。我创建了一个继承自 NSObject 的 VideoObserver 类，并将其设置如下：

@implementation VideoObserver

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if ([keyPath isEqualToString:@"status"]) {
        NSLog(@"Change: %@", change);
    }
}
@end

在 AVPlayerViewController 中，我将观察者设置为属性，然后使用它开始观察：

self.observer = [VideoObserver new];

NSURL * videoURL = [NSURL URLWithString:@"http://www.quirksmode.org/html5/videos/big_buck_bunny.mp4"];
self.videoPlayer = [AVPlayer playerWithURL:videoURL];

[self.videoPlayer addObserver:self.observer forKeyPath:@"status" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionInitial context:nil];

我已经在 Github 上发布了我的演示项目。