title: Trouble with negating Core Data NSPredicate relationships
body: <p>I'm scratching my head on this one. I have a work around, but I don't understand it so that doesn't count. What I want to do is for the entity (in this case a "Photo" lets say), I want to find all the Photos reviewed by anyone OTHER than the specified user. The relationship here is Photo->Review->User, where a photo can have multiple reviews, and each review is owned by exactly one user. The first two examples were my logical first attempts, but does not work. I found some similar code that shows the subquery which works, but can anyone explain why the first two examples don't work?</p>
  
  <pre><code>// this does not work
  [NSPredicate predicateWithFormat:@"NOT (ANY reviews.user = %@)", self.user]
  
  // this does not work
  [NSPredicate predicateWithFormat:@"NONE reviews.user = %@", self.user]
  
  // this works
  [NSPredicate predicateWithFormat:@"SUBQUERY(reviews, $x, $x.user == %@).@count == 0", self.user];
  </code></pre>