I am working on an auto-renewable subscription IAP in my iOS app. I plan to have 3 different tiers within the same subscription group. In my testing, I have been able to successfully purchase a subscription, see that it renews for a few times on sandbox and then stops after 5 or 6 tries. This part works fine.
But I want to try upgrading from one tier to a higher tier from the app. This time, when I try to add a SKPayment with the new (upgraded) productID to the payment queue, I first get an alert "Do you want to modify your subscription to ...", and after I hit continue, I get a confirmation message, but I also get a callback in SKPaymentQueue: updatedTransactions
with state Failed. The error says:
"failed transaction error = Error Domain=SKErrorDomain Code=0 "Cannot connect to iTunes Store" UserInfo={NSLocalizedDescription=Cannot connect to iTunes Store}
Any ideas why this might be happening, and whether it's even possible to test for subscription group updates from the sandbox? If not, then how would you go about testing this?