title: Handle streaming events with AVPlayer
body: <p>I'm building an app which plays an audio stream (from a webradio).</p>
  <p>I'm using <code>AVPlayer</code> for it.</p>
  <ol>
  <li><p>I'd like to know how you would handle <code>AVPlayer's</code> &quot;buffering&quot; when the connection is slow or when the user just clicked &quot;play&quot;. I want to detect that <code>AVPlayer</code> is &quot;buffering&quot; to display an <code>UIActivityIndicatorView</code>.</p>
  </li>
  <li><p>Same question while running in the background. What should I do if buffering in this case?</p>
  </li>
  </ol>