Apple server to server notifications with multiple triggers

Question

Apple states that for some subscription events they trigger multiple notifications. Suppose I wish to find out whether the user has cancelled their subscription so that I can offer them another cheaper option.

I could listen to DID_CHANGE_RENEWAL_STATUS to determine when they turned auto-renew off. However, there is a problem – the same notification will trigger if a user has upgraded to another SKU. In fact, according to their docs, it will trigger three notifications: CANCEL, DID_CHANGE_RENEWAL_STATUS, INTERACTIVE_RENEWAL.

I would like to distinguish between these scenarios. Obviously, as these are asynchronous operations, the order of arrival is not guaranteed. However, I wonder whether I can expect that all three notifications will arrive with the same unified_receipt? If so, I could listen for DID_CHANGE_RENEWAL_STATUS notification, check the unified_receipt and, if I see that my user has not signed up to another product, I can offer them another subscription option.

However, the docs do not mention whether Apple guarantees that in cases when multiple notifications are sent, all will arrive with the same unified_receipt. It would be logical... But it would also be logical to make notification_type an array to simplify things. And, given that Apple hasn't done it, I am worried that we cannot expect unified_receipt to be the same for successive notifications.

Has anyoned had an experience with this which you could share?

Answer 1

In the documentation for today (20210404) you can see that the multiple notifications have changed (comparing them to the ones active in September 2020). For example, and upgrade have passed from 3 to 2 notifications (CANCEL isn't sent, if the documentation doesn't lie...).

Perhaps you can detect what you need looking into the pending_renewal_info field. And the original_transaction_id should be the same in all the multiple notifications.

Perhaps the code sample in https://developer.apple.com/documentation/storekit/in-app_purchase/subscriptions_and_offers/determining_service_entitlement_on_the_server can give you some ideas about how to manage the information in the notifications.

The code sample show how to extract information from notifications; it doesn't give the exact response to your question, but can give you some insights about how manage them.