title: dispatch_async task problems with context
body: <p>I am using a <code>dispatch_async</code> task to retrieve a list with some contacts.<br>
  When selecting a contact from this list, I call Storage Manager to retrive some further information for this contact.<br>
  I get the error: <strong><em>Illegal attempt to establish a relationship</em></strong>...between objects in different contexts.<br>
  How to solve this?<br>
  Here is my code:</p>
  
  <pre><code> dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
        sections = [self getContactList];
     });
  
  informationList = [StorageManager getInfoForContact:[sections objectAtIndex:1]];
  </code></pre>
  
  <p>The error is at the line with informationList. Can someone help me to solve this? </p>