title: Crash using Aggregate Operation: "ALL" in a Core Data iOS Application
body: <p>I'm working on an iphone application and I have a simple many-to-many relationship set up with Group and Contact objects. A group can have many contacts and contacts can belong to multiple groups.</p>
  
  <p>I'm trying to select all groups that a particular contact does NOT already belong to using the following predicate. (Note: the uid field is a string field that I used to uniquely identify contact entities)</p>
  
  <pre><code>[NSPredicate predicateWithFormat:@"ALL contacts.uid != %@", contactUId]
  </code></pre>
  
  <p>According to Apple's Predicate Programming Guide, the ALL aggregate operation is valid but I get the following exception indicating that this is an unsupported predicate:</p>
  
  <pre><code>*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unsupported predicate (null)'
  </code></pre>
  
  <p>I can use a similar predicate to select all groups that a contact does already belong to using this predicate so it appears that I have all of the relationships and fields defined properly.</p>
  
  <pre><code>[NSPredicate predicateWithFormat:@"ANY contacts.uid == %@", contactUId]
  </code></pre>
  
  <p>The exception is thrown when constructing the predicate and not when I'm trying to actually execute the fetch request so it seems to be related to the syntax I'm using rather than Core Data support. What am I doing wrong?</p>