title: How to get URL for a PHAsset?
body: <p>I am using a third party library to select multiple images from the Photo Library. On selecting multiple images it returns an array of PHAsset objects.
  Now, I want to save the URL (or some reference) for these objects in the core data. But I do not know how to get the URL. Is there any other reference I could store in the core data which could help me in fetching the same image from the photo library? </p>