Detecting a cancelled itunes login alert for in-app purchases

Question

I have a class that implements SKPaymentTransactionObserver. However when clicking a buy button, if the user is not signed into the app store they get an alert asking for an existing ID or to create a new one. If the use clicks cancel from this, or a subsequent login credentials alert, I receive no notification of that cancellation. I have an activity view covering the screen after the buy button is clicked so I really need to know if the login alert was cancelled.

I already test for the error code SKErrorPaymentCancelled and that works if the purchase process is cancelled after logging in. I'm testing on a device.

Any clues?

-UPDATE-

Apologies I forgot to mention that this only happened when attempting to restore transactions, and that reveals the answer: my lack of knowledge about the protocol.

Answer 1

To detect the cancel event after a user tries to cancel a restore purchases request implement:

- (void)paymentQueue:(SKPaymentQueue *)queue restoreCompletedTransactionsFailedWithError:(NSError *)error
{
    // test error.code, if it equals SKErrorPaymentCancelled it's been cancelled
}

Answer 2

In Swift 3.0

public func paymentQueue(_ queue: SKPaymentQueue, restoreCompletedTransactionsFailedWithError error: Error) {
        print("Cancel Transaction");
    }

Answer 3

In Swift 2.2

public func paymentQueue(queue: SKPaymentQueue, restoreCompletedTransactionsFailedWithError error: NSError) {
    print("Cancel Transaction")

}