iOS 9:AVPlayerViewController在添加观察员后失去控制

Question

在向AVPlayer添加观察员后，我突然失去了对AVPlayerViewController的控制。

-(void)viewDidAppear:(BOOL)animated {
    AVPlayerItem *playerItem = [[AVPlayerItem alloc]initWithURL:_playbackInfo.streamURL];
    // logo to show
    CGRect  viewRect = CGRectMake(10, 10, 30, 30);
    UIView *overlayView = [[UIView alloc] initWithFrame:viewRect];
    UIImageView *image = [[UIImageView alloc]initWithFrame:viewRect];
    image.image = _playbackInfo.logoType;
    [overlayView addSubview:image];
    self.player = [[AVPlayer alloc]initWithPlayerItem:playerItem];
    [self.contentOverlayView addSubview:overlayView];
    self.player.actionAtItemEnd = AVPlayerActionAtItemEndNone;
    [self.player addObserver:self
                  forKeyPath:@"rate"
                     options:NSKeyValueObservingOptionNew
                     context:NULL];

    [self.player play];
    [self.navigationController setNavigationBarHidden:YES animated:NO];
}

- (void)observeValueForKeyPath:(NSString *)keyPath
                      ofObject:(id)object
                        change:(NSDictionary<NSString *,id> *)change
                       context:(void *)context {
    if ([keyPath isEqualToString:@"rate"]) {
        float rate = [change[NSKeyValueChangeNewKey] floatValue];
        if (rate == 0.0) {
            _sessionStarted = NO;
            NSLog(@"Playback stopped");
        } else if (rate == 1.0) {
            if(!_sessionStarted) {
                LTSessionManager *sessionManager = [LTSessionManager sharedInstance];
                sessionManager.delegate = self;
                [sessionManager startSessionManager:self.playbackInfo];
                [sessionManager getSessionStatus];
                NSLog(@"Start session");
                _sessionStarted = YES;
            }
        } else if (rate == -1.0) {
            // Reverse playback
        }
    }
}

每次当我移除- (void)observeValueForKeyPath:时，控件都会回来，但之后我就不会得到观察员了。有什么想法吗？提前谢谢。

Answer 1

可能为时已晚，但希望能在其他人遇到这个问题时提供帮助。我发现AVPlayerViewController有自己的观察器，可以调用-(void)observeValueForKeyPath:

解决方案是调用super.observeValueForKeyPath:，我将在Swift中显示代码：

override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
    if keyPath == "rate" {
        //your code here
    } else {
        super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
    }
}

Answer 2

在您的代码中，您没有将self.player添加到任何视图中。这就是为什么它没有在视图中显示球员的原因。试试这个例子：

-(void)viewDidAppear:(BOOL)animated {
 AVAsset *asset = [AVAsset assetWithURL: [NSURL URLWithString: "Your  video URL here"]];
        AVPlayerItem *item = [[AVPlayerItem alloc] initWithAsset:asset];
        AVPlayer *player = [[AVPlayer alloc] initWithPlayerItem:item];
        player.actionAtItemEnd = AVPlayerActionAtItemEndNone;
        AVPlayerLayer *layer = [AVPlayerLayer playerLayerWithPlayer:player];
        UIView *containerView = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0, 320.0f, 200.0f)];
        layer.frame = self.view.frame;
        [containerView.layer addSublayer:layer];
        [self.view addSubview:containerView];
        layer.backgroundColor = [UIColor greenColor].CGColor;
        [layer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
        [player play];
}

- (void)observeValueForKeyPath:(NSString *)keyPath
                      ofObject:(id)object
                        change:(NSDictionary<NSString *,id> *)change
                       context:(void *)context {
    if ([keyPath isEqualToString:@"rate"]) {
        float rate = [change[NSKeyValueChangeNewKey] floatValue];
        if (rate == 0.0) {
            _sessionStarted = NO;
            NSLog(@"Playback stopped");
        } else if (rate == 1.0) {
            if(!_sessionStarted) {
                LTSessionManager *sessionManager = [LTSessionManager sharedInstance];
                sessionManager.delegate = self;
                [sessionManager startSessionManager:self.playbackInfo];
                [sessionManager getSessionStatus];
                NSLog(@"Start session");
                _sessionStarted = YES;
            }
        } else if (rate == -1.0) {
            // Reverse playback
        }
    }
}