title: How to move sound from left to right of earphones in swift?
body: <p>I am making an app for blind people with swift and I can play sound only on the right headphone or only on the left by using the pan property like this:</p>
  
  <pre><code>@IBAction func right(sender: UIButton) {
      player.pan = 1.0 //right headphone
  }
  
  
  @IBAction func left(sender: UIButton) {
      player.pan = -1.0 //left headphone
  
  }
  </code></pre>
  
  <p>But I need to start playing sound in the right and then move it to the left headphone, how can I do this?</p>