Upgrading a paid app to free app

Question

I have a paid app(version 1.3) on app store. I want to release update(version 1.4) which has in app purchases. I am planning to release the update(version 1.4) which will be free .

I have covered all the possible scenarios for the upgrade of user from paid to free version . There is only one scenario where i am stuck.

1. User has already downloaded version 1.3 which is paid app via iTunes account [email protected] on iPad 2
2. Current available version on iTunes is 1.4 which is free.
3. User downloads the version 1.4 on the on iPad 2 [upgrade works as i can get the previous UserDefaults keys to identify]
4. User download the version 1.4 on iPhone 6 which din't have version 1.3 by [email protected] [How to know that user has already purchased the app ?]

Does anyone know what can be the solution for this problem.

Answer 1

Lev Landau's comment is right. If you don't have a server integration, you have to store something locally on the user's device in a 1.3.1 version. But you will have troubles with users who own multiple devices (i.e. iPhone and iPad). I can think about 3 ways to fix that:

1. Make sure that your "already bought" flag is saved on iCloud
   or
2. Use a free In-app purchase as a flag (RIP user experience).
   or
3. Release a NEW app with a new App ID for 1.4 and release a 1.3.1 that will warn your users about the new app and will let an entry in Keychain that you will retrieve in the new app (see this answer to see how to share keychain data between apps)

Note that methods 1 and 2 will not work for 100% of the users (if they don't open 1.3.1 before 1.4 for example). I would recommend method 3.