macOS Copy Detection

Basically, I'm trying to detect when the user has copied something to the clipboard and perform an action. In this case, I am trying to play a sound; I have imported the sound file to Xcode. However, It crashes because of the while loop and if I remove the while loop it still crashes because I restart the program in the end. How should I go about doing this because I always end up in a loop and eventually program crashes and can't detect a change in the NSPasteboard's changeCount. Also the sound file does not work, and I can't seem to figure out why. Any help would be awesome!!!! Writing it in Swift only.

Edit 1: I know why it's crashing, I just don't know any other way to do it.

import Cocoa
import AVFoundation

class ViewController: NSViewController {
let pasteboard = NSPasteboard.general

override func viewDidLoad() {
    super.viewDidLoad()

    let sound = URL(fileURLWithPath: Bundle.main.path(forResource: "sound", ofType: "mp3")!)

    var audioPlayer: AVAudioPlayer?

    //intializing audio player
    do
    {
        try audioPlayer = AVAudioPlayer(contentsOf: sound)

    }catch{
        print("fail")
    }


    let lastChangeCount=pasteboard.changeCount

    //keep looping until something is copied.
    while(pasteboard.changeCount==lastChangeCount){

    }

    //something is copied to clipboard so play audio
    audioPlayer?.play()

    //restart program
    self.viewDidLoad()

  }