title: Are the accessor methods created by to-many relationships as good as NSFetchedResultsControllers?
body: <p>My question is similar this one here:</p>
  
  <p><a href="https://stackoverflow.com/questions/8736692/resultscontroller-to-another-resultscontroller">ResultsController to another ResultsController</a></p>
  
  <p>A typical app structure on ios is to drill down into data via table views, and plenty of app models are hierarchical.  For example, a Film Festival could have many Films, which could have many Screenings, which could have many Attendees.  If we use Core Data to represent this model, then we can use an <code>NSFetchedResultsController</code> to populate Films into a <code>UITableView</code>.  Using the <code>NSFetchedResultsController</code> helps greatly with performance and memory efficiency, and provides built-in support for observing changes to the underlying data.  I would like to take advantage of this in my project as much as I can.</p>
  
  <p>So if we have a table of Films backed by this sweet <code>NSFetchedResultsController</code>, and the user selects a Film to see a list of its Screenings, we can pass that Film (a subclass of <code>NSManagedObject</code>) to a new <code>UITableViewController</code> and populate that table with the film's screenings.</p>
  
  <p>The core of my question is not "How do I do this?"  Instead, it's asking if the benefits of <code>NSFetchedResultsController</code> travel along with the <code>NSManagedObject</code>.  I could build a new results controller using the event in the predicate, but I don't need to.  If I pass the Film object into a variable called <code>film</code>, and my to-many relationship is identified as <code>screenings</code>, then I believe I can get the set of screenings related to that film like this:</p>
  
  <pre><code>NSSet *filmScreenings = [film screenings];
  </code></pre>
  
  <p>If I turn that set into an array, and use that as the data backing my new table view of screenings, am I losing the benefits of the <code>NSFetchedResultsController</code>?  My gut tells me yes, especially the support for monitoring changes - but an FAQ in Apple's docs made me second guess and ask the community at large.  Check out the question <a href="http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/CoreData/Articles/cdFAQ.html#//apple_ref/doc/uid/TP40001802-242985" rel="nofollow noreferrer">in this FAQ</a> called "I have a to-many relationship from Entity A to Entity B..."</p>
  
  <p>Should I use that accessor method then, or should I build a new <code>NSFetchedResultsController</code>?</p>