swift 3 Avplayer layer not visible while playing same video second time - ios

Question

In my application I have used AVPlayer to play videos, If we play a video and go bock to previous page video is playing in backgraound well but if we play the same video again we have to show continuation of the video and it should not begin from start , Here I can able to set slider position according to the video duration but the screen not showing video content sound is coming.
For first time to play any video i called below method
func setup() {
UserDefaults.standard.set(videoString as NSString, forKey: CurrentURL)
UserDefaults.standard.synchronize()
let targetTime:CMTime = CMTimeMake(0, 1)
mediaPlayer.seek(to: targetTime)
mediaPlayer.pause()
print("Video URL \(videoString)")
let url = NSURL(string: videoString)
let playerItem = AVPlayerItem(url: url! as URL)
mediaPlayer=AVPlayer(playerItem: playerItem)
let playerLayer=AVPlayerLayer(player: mediaPlayer)
playerLayer.frame = self.view.bounds
playerLayer.backgroundColor = UIColor.black.cgColor
//playerLayer.videoGravity = AVLayerVideoGravityResize
playerLayer.videoGravity = AVLayerVideoGravityResizeAspect
self.view.layer.addSublayer(playerLayer)
AppDelegate.shared().showLoading()
videoView.isHidden = false
mediaPlayer.play()
let duration : CMTime = mediaPlayer.currentItem!.asset.duration
let seconds : Float64 = CMTimeGetSeconds(duration)
videoSlider.maximumValue = Float(seconds)
videoPlayButton.setImage(UIImage(named: "Pause"), for: .normal)
videoPlaying = true
//Adding Default Periodic Observer On Player
mediaPlayer.addPeriodicTimeObserver(forInterval: CMTimeMakeWithSeconds(1, 1), queue: DispatchQueue.main) { (CMTime) -> Void in
if mediaPlayer.currentItem?.status == .readyToPlay {
AppDelegate.shared().removeLoading()
self.videoSlider.value = Float(CMTimeGetSeconds(mediaPlayer.currentTime()))
let currentTime : Int = Int(CMTimeGetSeconds(mediaPlayer.currentTime()))
let minutes = currentTime/60
let seconds = currentTime - minutes * 60
self.durationLabel.text = NSString(format: "%02d:%02d", minutes,seconds) as String
}
}
}
If user plays same video second time i'm checking current url which is stored in userdefaults if it is playing same video i did like following
let runningSrtring = UserDefaults.standard.object(forKey: CurrentURL) as! NSString
if runningSrtring.isEqual(to: videoString) {
//self.view.layer.sublayers?.forEach { $0.removeFromSuperlayer() }
videoPlayButton.setImage(UIImage(named: "Pause"), for: .normal)
let duration : CMTime = mediaPlayer.currentItem!.asset.duration
let seconds : Float64 = CMTimeGetSeconds(duration)
self.videoSlider.value = Float(CMTimeGetSeconds((mediaPlayer.currentTime())))
videoSlider.minimumValue = 0
videoSlider.maximumValue = Float(seconds)
let playerLayer = AVPlayerLayer(player: mediaPlayer)
playerLayer.frame = self.view.frame
playerLayer.backgroundColor = UIColor.black.cgColor
//playerLayer.videoGravity = AVLayerVideoGravityResize
playerLayer.videoGravity = AVLayerVideoGravityResizeAspect
self.view.layer.addSublayer(playerLayer)
mediaPlayer.addPeriodicTimeObserver(forInterval: CMTimeMakeWithSeconds(1, 1), queue: DispatchQueue.main) { (CMTime) -> Void in
if mediaPlayer.currentItem?.status == .readyToPlay {
self.videoSlider.value = Float(CMTimeGetSeconds((mediaPlayer.currentTime())))
let currentTime : Int = Int(CMTimeGetSeconds(mediaPlayer.currentTime()))
let minutes = currentTime/60
let seconds = currentTime - minutes * 60
self.durationLabel.text = NSString(format: "%02d:%02d", minutes,seconds) as String
}
}
}
But the lauer is not showing video content if i play same video again , here if the user play same video which is already running it should continue from current duration instead of restarting