We want to use auto-renewable subscriptions in our app (iOS/Android). But I don't understand what is the best way to sync these subscriptions between devices and platforms.
We are using user email for authentification but it seems that all subscriptions are linked to user's Apple account.
- Does it mean that I can't sell subscription to some user if another user (from the same device) already bought one on this device because this device is already subscribed?
- What is the best way to sync subscriptions between platforms? Should I write some server code to check subscription status for the current user? But, again, right now I don't have any information about user except his/her email. Of course, it is possible for me to put subscription status on our server but what to do with this case:
- user A bought auto-renewable subscription on iPhone from the app;
- user A cancelled this subscription via subscription management (app doesn't know anything about it yet)
- user A logged-in on Android device, and he is subscribed because I don't have any information about him/her cancelling his subscription yet.
I understand that I am able to check his/her subscription status from my server, but his/her in this case means I am able to check his/her Apple account status, not his/her account in my app. So, for example, if I have two/three/million users on the same Apple device (first is a paying user, and the second cancelled his subscription) it means that I will always get the good receipt from Apple, right?
It's possible that my understanding of how it works is not very good, or, maybe, I can't see the good working pattern here, but I don't understand how to create convenient subscriptions that would work for iOS/Android both.
At the same time I know it's possible because of Wunderlist and dozen other apps with this functionality. Could someone please describe high-level logic behind that?
