I have an unity activity, which launches in another process than my App:
The current implementation of
SharedPreferences in Android is not process-safe.
From the docs:
Note: currently this class does not support use across multiple processes. This will be added later.
The question is do you really need multiple processes in your application?
If you really do, i would suggest you to take a look at Tray, or consider some other form of persistent storage, such as a database.
Check out this answer also.