title: PHFetchOptions mediaSubtype predicate
body: <p>Following predicate should fetch all the screenshots only, which work just fine.</p>
  
  <pre><code>options.predicate = [NSPredicate predicateWithFormat:@"(mediaSubtype &amp; %d) != 0", PHAssetMediaSubtypePhotoScreenshot];
  </code></pre>
  
  <p>However if I try to exclude screenshots only by using follwing predicate, all of the images are excluded</p>
  
  <pre><code>options.predicate = [NSPredicate predicateWithFormat:@"(mediaSubtype &amp; %d) = 0", PHAssetMediaSubtypePhotoScreenshot];    
  </code></pre>
  
  <p>All Im trying to do is to exlude screeshots from asset fetch.</p>
  
  <p>Is this known bug or am I missing something ?</p>