title: dispatch_async on main_queue?
body: <p>I have seen this code snippet:</p>
  
  <pre><code>dispatch_async(dispatch_get_main_queue(), ^{
      [self doSomeNetworkStuff];
  });
  </code></pre>
  
  <p>This doesn't look like making much sense to me. </p>
  
  <p>EDIT: To clarify the conditions of my question:</p>
  
  <ul>
  <li>The call to <code>dispatch_async</code> is performed from the main thread.</li>
  <li>The sent message <code>doSomeNetworkStuff</code> is the heavy lifting worker task.</li>
  <li>... and is not only the UI-updating task.</li>
  </ul>
  
  <p>Dispatch, sure, but using the main queue would just pull the dispatched task back to the ui thread and block it.</p>
  
  <p>Please, am I missing something?
  Thanks.</p>