title: Any example on how to implement the new VerificationController and the KNOWN_TRANSACTIONS_KEY constant?
body: <p>I've been looking at implementing the new VerificationController to verify in-App-Purchases:
  <a href="http://developer.apple.com/library/ios/#releasenotes/StoreKit/IAP_ReceiptValidation/_index.html" rel="noreferrer">http://developer.apple.com/library/ios/#releasenotes/StoreKit/IAP_ReceiptValidation/_index.html</a></p>
  
  <p>And I wonder if there is some example anywhere en how to validate a transaction, since it seems that the <code>- (BOOL)verifyPurchase:(SKPaymentTransaction *)transaction;</code> is not enough and it has to be implemented internally to verify the purchase when the data form the server is received.  </p>
  
  <p>Another question is if anyone has a clue on what the KNOWN_TRANSACTIONS_KEY is and how to fill it, is it just the product id of the purchase? </p>