gistfile1.txt

    override func viewWillAppear(_ animated: Bool) {
        let url =  URL(string: "https://www.hrupin.com/wp-content/uploads/mp3/testsong_20_sec.mp3")!
            self.playSound(url: url)
            addPeriodicTimeObserver()
    }
    
    
     var player: AVAudioPlayer?

    func playSound(url: URL) {

        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
            try AVAudioSession.sharedInstance().setActive(true)

                player = try AVAudioPlayer(contentsOf: url)
                player?.play()
        } catch let error {
            print(error.localizedDescription)
        }
    }
    
    

    
    var player2: AVPlayer!
    var timeObserverToken: Any?
    
    func addPeriodicTimeObserver() {
      
        // Invoke callback every half second
        let interval = CMTime(seconds: 0.01,
                              preferredTimescale: CMTimeScale(NSEC_PER_SEC))
        // Queue on which to invoke the callback
        let mainQueue = DispatchQueue.main
        // Add time observer
        timeObserverToken =
            player2?.addPeriodicTimeObserver(forInterval: interval, queue: mainQueue) {
                [weak self] time in
                // update player transport UI
                print("time is \(time)") //it is never called
        }
    }