title: Unique identifier of photos in iPhone photo library
body: <p>I am going to develop an app that will basically work as a catalogue for the photos taken from  an iPhone app (saved in photo library). I am thinking about creating an SQLite database (catalogue) and mapping it to photos in the photo library (correct me if this approach is wrong).</p>
  
  <p>What would be the best way to map the photos and the SQLite database?</p>
  
  <p>I want to avoid the case that user changes name of the file and link between file and DB doesn't work anymore. </p>