禁用AVPlayerViewController的全屏按钮

Question

我正在使用将AVPlayerViewController视频嵌入到我的视频中UIView：

class MyView : PopupContentView {
    var player : AVPlayer!;
    var playerViewController: AVPlayerViewController!;

    override func awakeFromNib() {

    }

    override func setupView() {
        super.setupView();

        self.setupVideo();
    }

    deinit {
        self.player.pause();
        self.player = nil;
    }

    func setupVideo() {
        let path = Bundle.main.path(forResource: "Lebensqualitaet", ofType:"mp4")
        let url = URL(fileURLWithPath: path!)

        self.player = AVPlayer(url: url);

        self.playerViewController = AVPlayerViewController();
        self.playerViewController.player = self.player;

        self.callbacks.getAVCallbacks()?.setAVPlayerReference(player: self.playerViewController.player!);
        self.callbacks.getViewControllerToPresent().addChildViewController(self.playerViewController);

        self.addSubview(self.playerViewController.view);

        self.playerViewController.view.frame = self.frame;
    }
}

在此AVPlayerViewController有一个将视频设置为全屏的按钮。是否可以禁用此按钮？我的问题是，如果视频设置为全屏，并且在禁用全屏后再次关闭整个视图，我不知道为什么。这就是为什么我只想禁用全屏模式的原因。