title: How to create an NSFetchRequest which filters Core Data objects based on attributes AND relationships?
body: <p>I have a Core Data model setup like so:</p>
  
  <ul>
  <li><strong>Blockbuster</strong> Entity
  
  <ul>
  <li>To-Many relationship to <strong>DVD</strong> entities.</li>
  </ul></li>
  <li><strong>DVD</strong> Entity
  
  <ul>
  <li><strong>title</strong> attribute (string)</li>
  <li>To-One relationship to a parent <strong>Blockbuster</strong> entity</li>
  </ul></li>
  </ul>
  
  <p>A single Blockbuster can have multiple DVD's inside of it (To-Many).  Each DVD can only be part of a single Blockbuster (To-One).</p>
  
  <p>There are multiple Blockbuster's, and some may contain DVD entities which share the same title as DVD entities from other Blockbuster's.  For example, <em>Blockbuster A</em> might have a copy of "Transformers 2", and so does <em>Blockbuster C</em> and <em>Blockbuster G</em>.  Let's pretend no Blockbuster has more than one copy of the same titled movie.</p>
  
  <p>I'm interested in grabbing the <em>Transformers 2</em> DVD from <em>Blockbuster C</em>.  I don't want the copies from <em>Blockbuster A</em> or <em>G</em>, because my boss frequents there, and I can only get away with burning this piece of garbage in <em>Blockbuster C</em>.</p>
  
  <hr>
  
  <p>My question is, how do I form an NSFetchRequest which grabs a <strong>DVD</strong> with the <strong>title</strong> "Transformers 2", which is a child of the <strong>Blockbuster</strong> "C" parent entity?</p>
  
  <p>This type of request will grab all the "Transformer 2" DVD's, but not the one specific to the Blockbuster C entity:</p>
  
  <pre><code>NSManagedObjectContext *moc = [self managedObjectContext];
  
  NSString *aTitle = @"Transformers 2";
  NSFetchRequest *request = [[NSFetchRequest alloc] init];
  NSPredicate *predicate = [NSPredicate predicateWithFormat:@"title == %@", aTitle];
  [request setEntity:[NSEntityDescription entityForName:@"DVD" inManagedObjectContext:moc]];
  [request setPredicate:predicate];
  
  NSError *error = nil;
  NSArray *results = [moc executeFetchRequest:request error:&amp;error];
  
  // error handling code
  [request release];
  </code></pre>
  
  <p>Is there a way to pass, say, the Object ID of a related object inside the NSPredicate, filtering based on that?</p>