ios – AVPlayer全屏

我在我的应用程序中使用AVPlayer而不是MPMoviePlayerController,因为我想将播放器作为子图层.
但是我需要控制,如播放,暂停,搜索和全屏.如何在AVPlayer中获得该按钮？
这就是我放置玩家的方式：

AVURLAsset *avasset = [[AVURLAsset alloc] initWithURL:URL1 options:nil];

    AVPlayerItem *item = [[AVPlayerItem alloc] initWithAsset:avasset];
    player = [[[AVPlayer alloc] initWithPlayerItem:item]retain];

    playerLayer = [AVPlayerLayer playerLayerWithPlayer:player];
    CGSize size = self.view.bounds.size;
    float x = size.width/2.0-187.0;
    float y = size.height/2.0 - 125.0;

    playerLayer.frame = CGRectMake(x,y,474,320);
    [playerLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [self.view.layer addSublayer:playerLayer];
    [player play];