Loop video using key value observer in Swift 3

loopVideo.swift

    var introPlayer: AVPlayer?
    var introPlayerLayer: AVPlayerLayer?
    fileprivate var playerObserver: Any?   

    let keyPathToObserve:String = "isReadyForDisplay"

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        if introPlayer == nil {
            playVideo()
        }
    }

    func playVideo() {
        let path = Bundle.main.path(forResource: "videoLoop", ofType: "mp4")
        let url  = NSURL.fileURL(withPath: path!)
        introPlayer = AVPlayer(url: url)
        if let introPlayer = introPlayer {
            introPlayer.allowsExternalPlayback = false
            introPlayerLayer = AVPlayerLayer(player: introPlayer)
            introPlayerLayer?.backgroundColor = UIColor.clear.cgColor
            introPlayerLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
            self.view.layer.insertSublayer(introPlayerLayer!, at: 0)
            introPlayerLayer?.frame = self.view.bounds
            introPlayer.rate = 1
            
            playerObserver = NotificationCenter.default.addObserver(forName: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: introPlayer.currentItem, queue: nil) { notification in
                self.resetPlayer()
            }
            
            // register for KVO change of the ready to play property
            // Note: need to keep a reference to the player layer for this to compile (?)
            addObserver(self, forKeyPath: #keyPath(introPlayerLayer.isReadyForDisplay), options: [.old, .new], context: nil)
        }
    }
    
    func resetPlayer() {
        introPlayer?.seek(to: kCMTimeZero)
        introPlayer?.play()
    }
    
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == #keyPath(introPlayerLayer.isReadyForDisplay) {
            self.backgroundImage.isHidden = true
        }
    }