title: How to preload a AVPlayerItem
body: <p>I understand that when using a <code>AVQueuePlayer</code> to play a list of <code>AVPlayerItem</code> objects the player preload the next item in queue for faster reload when user get to this item.    </p>
  
  <p>The problem is that I need to have more control of which items preload, for example I want that the 3 next song and the 2 previous song be preloaded and prepare for fast loading.  </p>
  
  <p>So I think to manage the <code>AVPlayerItem</code> objects myself, I just not sure how do I preload a <code>AVPlayerItem</code>?<br>
  How can I preload the first 30 seconds for example?  </p>