This is not a question on what storing system use, but is a question on what are the possible strategies to store data locally on a mobile platform (iOS and Android).
I wouldn't use AsyncStorage because data is not encrypted, I see that Realm could be a good candidate, however I am open to other alternatives.
My cross-platform React Native application handles some sensible data that should be persistent on the device. The meaning of persistent that I intend is:
Some sensible data that must be not removed/deleted/cleared by iOS or Android without the permission of the user. Data that must be available at each application upgrade, e.g. at each new release, these data must be remain unchanged and available like nothing happened after App update. Data must not be removed/deleted/cleared if the App is put in background (task manager), turned off or restarted. Data must be available even if the device is rebooted.
I tried each of these cases by using Realm and it seemed to be very good, but since I have not so much experience in mobile development, I preferred to ask the community if my considerations about Realm are correct or not. If no, I would ask what are the possible alternatives and why I am wrong.
Unfortunately, I have no permission to use cloud storages (e.g. CloudKit, iCloud, Firebase and so on...). My App must handle this data only locally on the device.
New scenario
Same identical previous restrictions of above (sensible data that must be not removed/deleted/cleared [...]), but considering the possibility to use cloud storage systems, what are the best good practices in this scenario, or better: where can I find out "a state of the art documentation" about these things for both platforms?