title: In-App purchasing: Listen for the "Cancel' button?
body: <p>I'm trying to figure out how I can listen to the "Cancel" button that appears in the "confirmation" alert shown when a user tries to purchase something. You know, the official one done by Apple, looks something like: "Confirm Your In App Purchase. Do you want to buy one $product for $price? [Cancel] [Buy]"</p>
  
  <p>If I understand my code correctly, the alert initiated by something like this:</p>
  
  <pre><code>SKPayment *payment = [SKPayment paymentWithProductIdentifier:productIdentifier];
  [[SKPaymentQueue defaultQueue] addPayment:payment];
  </code></pre>
  
  <p>So basically I'd like to do something if they hit Cancel. Thanks</p>