title: PHFetchOptions for PHAsset in same sort order as Photos.app
body: <p>I'm using the new PHFetchOptions' sortDescriptors for getting PHAssets from the camera roll. There seem to only be two keys to sort on: creationDate and modificationDate, neither of which are the same as what you see in the Photos.app.</p>
  
  <p>Am I missing something? How can we get this to work?</p>