Make a video loop effect like boomerang

Im trying to make a video loop from an mp4 file. Like in the boomerang from instagram app, I have this code

class ViewController: UIViewController {

    var avPlayer: AVPlayer!
    var avPlayerLayer: AVPlayerLayer!
    var paused: Bool = false
    var reverse: Bool = true

    override func viewDidLoad() {
        super.viewDidLoad()
        let theURL = Bundle.main.url(forResource:"vidio", withExtension: "mp4")

        avPlayer = AVPlayer(url: theURL!)
        avPlayerLayer = AVPlayerLayer(player: avPlayer)
        avPlayerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        avPlayer.volume = 0
        avPlayer.actionAtItemEnd = .none

        avPlayerLayer.frame = view.layer.bounds
        view.backgroundColor = .clear
        view.layer.insertSublayer(avPlayerLayer, at: 0)

        NotificationCenter.default.addObserver(self,
                                               selector: #selector(playerItemDidReachEnd(notification:)),
                                               name: NSNotification.Name.AVPlayerItemDidPlayToEndTime,
                                               object: avPlayer.currentItem)
    }

    func playerItemDidReachEnd(notification: Notification) {

        guard reverse else {
            avPlayer.seek(to: kCMTimeZero)
            avPlayer.rate = 1.0
            reverse = true
            print("normal")
            return
        }

        print("reversa")

        avPlayer.seek(to: avPlayer.currentItem!.duration,
                    toleranceBefore: kCMTimeZero,
                    toleranceAfter: kCMTimeZero)
        avPlayer.rate = -1.0

        reverse = false
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        avPlayer.play()
        paused = false
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        avPlayer.pause()
        paused = true
    }
}

But when the video reverse, it doesn 't look smooth and the reverse doesn' t start from the last part of the video. Any Ideas how to solve this? I want the video to look smooth like in the boomerang app loop