title: How to Autorelease a CGImageRef?
body: <p>I have a method that returns a <code>CGImageRef</code> object. It contains this call:</p>
  
  <pre><code>CGImageRef posterFrame = [avAssetImage copyCGImageAtTime:time actualTime:nil error:&amp;error];
  ...
  return posterFrame;
  </code></pre>
  
  <p>This situation, as I understand it, calls for an autorelease. But I have no idea how to do it. I've tried using <code>CFCollectable()</code>, but it doesn't work. Any ideas?</p>