title: Initializing an AVPlayerItem with automaticallyLoadedAssetKeys and "duration"
body: <p>I'm initializing an <code>AVPlayerItem</code>, and it takes a parameter <code>automaticallyLoadedAssetKeys</code>, which indicates which <code>AVAsset</code> keys need to be loaded before it is flagged as "ready to play".</p>
  
  <p>I've seen examples of people passing in the <code>duration</code> property as one of these keys.</p>
  
  <p>But then over in the documentation for <code>AVPlayerItem</code>, it talks about the <code>duration</code> property, and how to make sure that it's valid.</p>
  
  <blockquote>
    <p>The value of this property will be reported as kCMTimeIndefinite until the duration of the underlying asset has been loaded. There are two ways to ensure that the value of duration is accessed only after it becomes available:</p>
    
    <p>Wait until the <code>status</code> of the player item is <code>readyToPlay</code></p>
  </blockquote>
  
  <p>The other way is to register a KVO, which is fine. But this first comment would indicate to me that I <em>do not</em> need to ask that <code>duration</code> gets automatically loaded, because it should be already.(?)</p>
  
  <p>If this is true, I can't figure out why anyone would ever pass in <code>duration</code> as a flag to be automatically loaded, because it looks like that's the case. Am I missing something here?</p>