displaying dialogue after in-app purchase complete - iphone

Question

I have implemented the SKPaymentTransactionObserver in my apps AppDelegate the way Apple recommended:
- (void) completeTransaction: (SKPaymentTransaction *)transaction
{
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:transaction.payment.productIdentifier];
[[SKPaymentQueue defaultQueue] finishTransaction: transaction];
}
- (void) restoreTransaction: (SKPaymentTransaction *)transaction
{
[[NSUserDefaults standardUserDefaults] setBool:YES forKey:transaction.payment.productIdentifier];
[[SKPaymentQueue defaultQueue] finishTransaction: transaction];
}
- (void) failedTransaction: (SKPaymentTransaction *)transaction
{
if (transaction.error.code != SKErrorPaymentCancelled)
{
// Optionally, display an error here.
}
[[SKPaymentQueue defaultQueue] finishTransaction: transaction];
}
- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response
{
self.products = response.products;
}
- (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions
{
for (SKPaymentTransaction *transaction in transactions)
{
switch (transaction.transactionState)
{
case SKPaymentTransactionStatePurchased:
[self completeTransaction:transaction];
break;
case SKPaymentTransactionStateFailed:
[self failedTransaction:transaction];
break;
case SKPaymentTransactionStateRestored:
[self restoreTransaction:transaction];
default:
break;
}
}
}
I'd like for my app to send a dialogue message to the user when the following happens: purchase successful, purchase failed, restore successful, restore failed. I'm having a little trouble wrapping my head around how I can do this with my design set up. I have a couple of questions:
1) The alert needs to be posted in the view controller where the transaction is initialized. How can I make the AppDelegate communicate with this view controller to let it know when an event has happened? Do I set up a delegate for the AppDelegate? This seems kind of funny to me...is there a better way?
2) Where do I send the message? Should it be in finishTransaction (do I need to override?) or somewhere else?

Answer 1

Passing a notification will be the best way for it. The view controller which invokes the payment procedure should register for notification.
On the completion of a transaction, app delegate will post the notification which controller will receive and it will show the appropriate message.