How to properly handle renewal of the autorenewable subscriptions (iOS) - ios

Question

Found this statement in apple documentation:
After a subscription is successfully renewed, Store Kit adds a
transaction for the renewal to the transaction queue. Your app checks
the transaction queue on launch and handles the renewal the same way
as any other transaction.
If I only do this on start:
[[SKPaymentQueue defaultQueue] addTransactionObserver:self];
Nothing happens - subscription is not renewed (using test mode).
if I add
[[SKPaymentQueue defaultQueue] restoreCompletedTransactions];
Then it runs over complete history of purchases which is also not what I want.
What is the proper way to handle it?

Answer 1

One thing you need to understand, when testing auto renewable subscription in sandbox environment, sometimes the subscription doesn't get renewed and you don't get renewal calls from the Store.
This is normal in sandbox and calling restoreCompletedTransactions in sandbox environment sometimes it trigger the renewal on the Store. The duration for the subscription itself is different in the sandbox: Here is a table of duration in sandbox:
Just add [[SKPaymentQueue defaultQueue] addTransactionObserver:self] when your app launches and in production it will get renewed and you will get calls.

Answer 2

Apple in-app purchase storkit document:-
After a subscription is successfully renewed, Store Kit adds a transaction for the renewal to the transaction queue. Your app checks the transaction queue on launch and handles the renewal the same way as any other transaction.
Which means,
If user's subscription is auto renewed and at that time our app is not running, Apple added that renewed transaction in transaction queue. So when you will opened app, we can get those renewed transaction details from transaction queue.
There is another statement mentioned in storekit document like:-
Note that if your app is already running when the subscription renews, the transaction observer is not called; your app finds out about the renewal the next time it’s launched.
Solution: How to handle auto-renewal subscription?
According to Apple storekit best practices, we should add below line in AppDelegate's "didFinishLaunchingWithOptions":-
SKPaymentQueue.defaultQueue().addTransactionObserver(SubscriptionObserverClassReference)
& for verifying subscription, Two ways available:
1) Using Server: Set cron job that verify user subscription arounds user's subscription expiration date. So we can identify user subscription renewed or not based on expiration date.
2) Using StoreKit Observer:- Every time when user subscription is renewed, we get renewed transaction information. So based on that we can take action accordingly.

Answer 3

The commentors and documentation were right: it is sufficient to add transaction observer to the PaymentQueue on start. In my case the renewal has not been triggered for the Sandbox User I used the whole time. I created the new one and it worked!

Answer 4

For my case, in sandbox testing for subscription, it will only auto renew the subscription for 5 only on the FIRST subscription purchase. Subsequent subscription purchase will stop renewing after purchase. The only way to test is to recreate a new sandbox user and test again. Rinse and repeat!