-(void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions
{
    for (SKPaymentTransaction *transaction in transactions)
    {
        switch (transaction.transactionState)
        {
            case SKPaymentTransactionStatePurchasing:
            {
                NSLog(@"Purchasing Product From Store!");
            }
            break;

            case SKPaymentTransactionStatePurchased:
            {
                 NSLog(@"Purchased Product From Store! %@", transaction.description);
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                if(buyProductBlock != nil)
                {
                    buyProductBlock(TRUE, nil);
                    buyProductBlock = nil;
                }
            }
            break;

            case SKPaymentTransactionStateRestored:
            {
                //SKPaymentTransactionStateRestored is only issued after you call restoreCompletedTransactions.
                NSLog(@"Restored");
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
            }
            break;

            case SKPaymentTransactionStateFailed:
            {
                NSLog(@"Purchase failed %@ %@", transaction.payment.productIdentifier, transaction.payment.debugDescription);
                [[SKPaymentQueue defaultQueue] finishTransaction: transaction];

                if(buyProductBlock != nil)
                {
                    if (transaction.error.code == SKErrorPaymentCancelled)
                        buyProductBlock(FALSE, nil);
                    else
                        buyProductBlock(FALSE, transaction.error.localizedDescription);
                    buyProductBlock = nil;
                }

            }
            break;


            default:
                break;
        }
    }
}

Test an Interrupted Transaction

Set a breakpoint in your transaction queue observer’s paymentQueue:updatedTransactions: method
so you can control whether it delivers the product. Then make a purchase as usual in the test
environment, and use the breakpoint to temporarily ignore the transaction—for example, by
returning from the method immediately using the thread return command in LLDB. Terminate and
relaunch your app. Store Kit calls the paymentQueue:updatedTransactions: method again shortly
after launch; this time, let your app respond normally. Verify that your app correctly delivers
the product and completes the transaction.