We are trying to implement simple In-App Purchases with StoreKit (not sure if it has anything to do with it) and everything went smooth so far, however there is one specific issue we are facing: When we exit the app, iOS permanently asks us to sign in:
This only happens when signed in with the sandbox or TestFlight accounts, but it is incredibly annoying. Is there any reason behind this or should we not worry about it ? I have read that many face a similar issue and that it would resolve once the app is in production, but it seems like a hacky/unpredictable way of dealing with it.
I'd be ready to provide more information if you require. At this point I just don't have a clue as to why this would happen (I have linked it with many things, but none of them really turned out correct... e.g. Receipt verification request, unfinished transaction in Payment Queue, etc.).
Normal behavior: it is the consequence to your device being logged out.
The short answer is: log-in again.
sandbox accounts
These accounts have a somewhat special behavior and will replace your Apple ID, possibly causing synchronization issues. For starters, you cannot login in from Settings > iTunes & App Stores and complete that login without entering a credit card number, which one generally declines for that very reason, while you can successfully log-in to a sandbox account from the In App Purchase section of an app.
Your personal account
Once you log-in with sandbox credentials, you effectively will be logged out from your personal one. A large combination of actions require your device to be logged in from a real account (as opposed to a sandbox one).
This includes, but is not limited to:
All these will trigger the Sign In to iTunes Store alert.