iOS IAP: How to veriy that user was really charged for transaction

Question

I am using

paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction])

and inside I am of course handling the transactionState . Everything is working fine, but now I want to add proper tracking.

There is the special case, when a user bought the SKPRoduct already before but hits the buy again (ie after a fresh install) Then he wont be charged again, but the transaction state will be .purchased even though it was a restore.

Is this only happening in the sandbox environment? I did not yet publish it so I don't have any live experience about this, but I wonder if there is a correct way to find out if the transaction was really a purchase, or in fact a restore?

Answer 1

First of all when user installs the app and clicks buy you dim the display and wait until delegate methods inform you that payment occurred successfully then you store a boolean in user defaults that user bought the IAP , whenever you open the VC with buy button check the boolean and hide/show it accordingly

Note: re-charge won't happen again if user deletes the app after purchase and installs it again and clicks buy