title: iOS Address Book - How To Know Which Contact Was Added/Edited/Deleted?
body: <p>My app needs to store a user's contacts on our servers (given the user's permission of course.) One of it's requirements is to reflect any changes on the devices address book (add/edit/delete) to the server.</p>
  
  <p>Is there an easy way/best practice with regards to determining which address book contacts were changed prior to re-launching an application?</p>
  
  <p>All I can see are callback methods to notify an application of a change in the address book, but it seems there are no documented ways to determine which contacts were added, edited, or deleted.</p>
  
  <p>What I'm thinking of right now is to manually compare the new list of contacts with one stored on the device, then update both the application and the server of the changes. But I think that it might be too much if the user has a big amount of contacts.</p>
  
  <p>Thanks!</p>