title: Apple rejected my App due to restore IAP
body: <p>I have a Restore button. The problem is if they havent' done a restore, and they try to purchase an item, and they have already purchased that item, I need to tell them they already purchased it and not perform the purchase. So I need a way to know, without doing a restore, which items they've purchased. I tried doing a restore first, whenever the user tries to purchase, but apple rejected my app. They said a restore cannot occur before the Confirm In-App Purchase dialog is displayed.</p>
  
  <p>Please help me to find the right way.</p>
  
  <p>Thanks in advance.</p>