Player

import UIKit
import MediaPlayer
import AVFoundation

class FirstViewController: UIViewController, MPMediaPickerControllerDelegate {

    
    
    @IBAction func loadMusic(_ sender: Any) {
    

         let mediaPicker: MPMediaPickerController = MPMediaPickerController.self(mediaTypes:MPMediaType.music)
        mediaPicker.delegate = self
        mediaPicker.allowsPickingMultipleItems = false
        self.present(mediaPicker, animated: true, completion: nil)
        
    }
    
    // MPMediaPickerController Delegate methods
    func mediaPickerDidCancel(_ mediaPicker: MPMediaPickerController) {
        self.dismiss(animated: true, completion: nil)
    }
    
    func mediaPicker(_ mediaPicker: MPMediaPickerController, didPickMediaItems mediaItemCollection: MPMediaItemCollection) {
        
     
        self.dismiss(animated: true, completion: nil)
        guard let mediaItem = mediaItemCollection.items[0] as? MPMediaItem else {return}
         let mediaItemURL = mediaItem.value(forProperty: MPMediaItemPropertyAssetURL) as! URL
       
        
            let theAsset = AVAsset(url: mediaItemURL as URL)
            if theAsset.hasProtectedContent {
                print("theAsset hasProtectedContent")
                return
            }
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
             self.playSound(url: mediaItemURL)
          
        }
       
    }//end didPickMediaItems
    

    
    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()
            
            self.addPeriodicTimeObserver()
            
        } catch let error {
            print(error.localizedDescription)
        }
    }
    
    

    
    var otherPlayer: AVPlayer!
    var timeObserverToken: Any?
    
    func addPeriodicTimeObserver() {
      
        // Invoke callback every half second
        let interval = CMTime(seconds: 0.5,
                              preferredTimescale: CMTimeScale(NSEC_PER_SEC))
        // Queue on which to invoke the callback
        let mainQueue = DispatchQueue.main
        // Add time observer
        timeObserverToken =
            otherPlayer.addPeriodicTimeObserver(forInterval: interval, queue: mainQueue) {
                [weak self] time in
                // update player transport UI
                print("time is \(time)") //it is never called
               
           
        }
    }
    

}