在iOS上使用youtube-ios-player-helper检测缩放和完成按钮

Question

class testYoutubeViewController: UIViewController, YTPlayerViewDelegate {

    @IBOutlet weak var playerView: YTPlayerView!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.playerView.delegate = self
        let playerVars = ["playsinline": 0, "showinfo":0, "controls": 0, "autohide":1]
        playerView.load(withVideoId: "OsINvu5FYKg", playerVars: playerVars)

        //playerView.load(withVideoId: "M7lc1UVf-VE")
        //playerView.playVideo()

        // Do any additional setup after loading the view.
    }

    override func viewDidAppear(_ animated: Bool) {
        playerView.playVideo()
    }

    func playerView(_ playerView: YTPlayerView, didChangeTo state: YTPlayerState) {
        switch state {
        case .playing:
            print("Stared Playback")
        case .paused:
            print("Paused")
        case .ended:
            print("Ended")
        case .buffering:
            print("buffering")
        case .unstarted:
            print("unstartd")
        case .queued:
            print("playing queued")
        default:
            break
        }
    }

    func playerViewDidBecomeReady(_ playerView: YTPlayerView) {
        playerView.playVideo()
    }

}

*我想添加一个观察者来检测我何时完成或放大youtube视频播放器。 *视频效果很好，能够控制播放，暂停，下一个视频，等等https://developers.google.com/youtube/js_api_reference#cuePlaylistObj。但是我没有看到用于检测完成和缩放按钮的事件示例。