title: Document-based app doesn't restore documents with non-file URLs
body: <p>I have an application based on NSDocument with an NSDocumentController subclass. My NSDocument works with both file URLs and URLs with a custom scheme which use a web service.</p>
  
  <p>I handle much of the loading and saving using custom code, including <code>-saveToURL:ofType:forSaveOperation:completionHandler:</code>. <code>+autosavesInPlace</code> returns <code>YES</code>.</p>
  
  <p>The problem I'm having: documents with the custom URL scheme aren't restored on startup. Documents with the file URL scheme are – both regular documents saved to files, and untitled documents which are autosaved.</p>
  
  <p>After leaving open server-based documents and quitting the app, no NSDocument methods appear to be called on restart. In particular, none of the four initializers is called:</p>
  
  <ul>
  <li>–init</li>
  <li>–initWithContentsOfURL:ofType:error:</li>
  <li>–initForURL:withContentsOfURL:ofType:error:</li>
  <li>–initWithType:error:</li>
  </ul>
  
  <p>The NSDocumentController method <code>-reopenDocumentForURL:withContentsOfURL:display:completionHandler:</code> is not called either.</p>
  
  <p>How and when are documents' restorable state encoded? How and when are they decoded?</p>