Transaction comes back after finishTransaction: has been called on it

Question

I am using in-app purchase for an iPhone app. I have a class that acts as SKProductsRequestDelegate and SKPaymentTransactionObserver, and it\'s all

Answer 1

I had this problem too. The bug turned out to be on my side. The problem was that there was a past transaction lurking around that had been executed (the content provided) but not cleaned up using finishTransaction. Unfortunately, on asking at several places including an Apple TSI, I discovered that there was no way to poll such 'undead' transactions - you just had to register for notifications and wait for the corresponding paymentQueue:updatedTransactions:. This complicated my code, but not by much.

What I do now, which has been working fine:

• When the store is about to be invoked (you're flashing some marketing slides, a terms of use maybe), fetch your product list and register for notifications as an observer via [[SKPaymentQueue defaultQueue] addTransactionObserver:self]
• Keep a state variable that gets updated to YES when you push a payment in the queue using [[SKPaymentQueue defaultQueue] addPayment:payment]
• When you get notified of a successful purchase via paymentQueue:updatedTransactions: check the state variable. If it has not been set, it means you have received a notification for a past payment. In that case, honor that payment rather than pushing a new one.

This method naturally assumes that you have the time to wait for old transactions to show up before starting a new transaction.