title: Run an anonymous block on a specific background thread
body: <p>At first glance it seemed like an easy question, but I just can't figure how to run an anonymous block on a certain background thread i.e. I am looking for the blocks equivalent of <code>-performSelector:onThread:withObject:waitUntilDone:</code>.</p>
  
  <p>Related: Is it possible to associate a dispatch queue with a certain background thread, just like the main queue is associated with the application's main thread?</p>
  
  <p><em>Edit</em> Clarified that I am looking to run an anonymous block</p>