title: When autorelease pool release object in background thread?
body: <p>I know autorelease pool will release objects when the runloop in the state <code>kCFRunLoopBeforeWaiting</code>.</p>
  
  <p>So I create a background thread which runloop doesn't run by default.</p>
  
  <p>If I use an autorelease pool in this background thread, when does it release objects.</p>