title: ALAssetsGroup issue with IOS 5
body: <p>My code was working on OS 4.3 
  but with 5 i am getting warnings regarding ALAssetsGroup 
  for the ALAssetsGroup i dont get any methods for it so i get instance not found for the enumerate 
  see code </p>
  
  <pre><code> void (^assetEnumerator)(ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop)
  {
      if(result != nil)
      {
          [assets addObject:result];
      }
  };
  
  
  // Create instance of the Assets Library.
  void (^assetGroupEnumerator)( ALAssetsGroup *, BOOL *) = ^(ALAssetsGroup *group, BOOL *stop) {
      if(group != nil)
      {
          [group enumerateAssetsUsingBlock:assetEnumerator];
      }
  };
  
  
  
  assets = [[NSMutableArray alloc] init];
  ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
  [library enumerateGroupsWithTypes:ALAssetsGroupAlbum
                         usingBlock:assetGroupEnumerator
                       failureBlock: ^(NSError *error) {
                           NSLog(@"failureBlock:%@",error);
                       }];    
  </code></pre>
  
  <p>Any help will be appreciated 
  Thanks</p>