title: When to use Core Data's NSMainQueueConcurrencyType?
body: <p>Is initializing a <code>NSManagedObjectContext</code> using <code>NSMainQueueConcurrencyType</code> only for the situation where that MOC has a child MOC that was initialized using <code>NSPrivateQueueConcurrencyType</code>?</p>
  
  <p>To give some background: my app has a traditional structure whereby the main table view is driven by a <code>NSFetchedResultsController</code> and data are imported asynchronously from a web service using an <code>NSOperation</code> subclass that has its own MOC. I wasn't sure whether both MOCs in that situation should use <code>NSConfinementConcurrencyType</code> (the default, I believe) or whether the MOC associated with the fetched results controller on the main thread should use <code>NSMainQueueConcurrencyType</code> and the background MOC should use <code>NSConfinementConcurrencyType</code>.</p>