title: CSSearchableItemAttributeSet init methods return nil
body: <p>I have some trouble with the new Core Spotlight API in iOS 9. The problem is that the init methods for CSSearchableItemAttributeSet returns nil. Here is an example that does not work for me:</p>
  
  <pre><code>CSSearchableItemAttributeSet* attributeSet = [[CSSearchableItemAttributeSet alloc] initWithItemContentType:(NSString *)kUTTypeImage];
  
  attributeSet.title = movie.movieName;
  attributeSet.contentDescription = movie.shortDescription ? movie.shortDescription : movie.longDescription;
  attributeSet.thumbnailURL = [NSURL URLWithString: [movie posterURLStringWithWidth:100]];
  </code></pre>
  
  <p>the attributeSet is nil directly from start, so the last three lines does nothing. I have added the CoreSpotlight and MobileCoreService framework to the project and imported them in the same file. I have tried <code>[[CSSearchableItemAttributeSet alloc] init]</code> and this as well returns nil. I really can't figure out what I'm doing wrong. Using Xcode 7.0 beta 4. Any idea why it would return nil is highly appreciated! </p>