title: Check if contact already present in abaddressbook
body: <p>I have a app which takes backup for contacts. All records are sent to server in <code>NSData</code> format.
  Also I have put restore functionality. Issue is duplicate record is created in phone contact.
  I wanted to compare <code>ABrecordId</code>. But when I restore and get vcard, its <code>ABRecordId</code> is -1.
  How can I solve this. Please help.</p>