I have the usual store kit queue observer code:

```
func paymentQueue(_ queue: SKPaymentQueue, 
    updatedTransactions transactions: [SKPaymentTransaction]) {
        for t in transactions {
            switch t.transactionState {
            case .purchasing, .deferred: break // do nothing
            case .purchased, .restored:
                let p = t.payment
                if p.productIdentifier == myProductID {
                    // ... set UserDefaults to signify purchase ...
                    // ... put up an alert thanking the user ...
                    queue.finishTransaction(t)
                }
            case .failed:
                queue.finishTransaction(t)
            }
        }
}

```

The problem is what to do where I have the comment "put up an alert thanking the user". It seems simple enough: I'm creating a UIAlertController and calling `present` to show it. But it sometimes doesn't appear!

The trouble seems to have something to do with the fact that the runtime puts up its own alert ("You're all set"). I don't get any notice of this so I don't know this is happening. How can I cause my UIAlertController to be presented for certain?