[iOS] AsyncStorage data persists after uninstalling and re-installing app

Current behavior

Using the latest stable release (1.9.0), AsyncStorage items that are set persist after an iOS app is uninstalled and then re-installed.

Expected behavior

AsyncStorage should be completely clear after uninstalling/reinstalling an app. This is how the framework bundled AsyncStorage behaves, so one would expect the community version to function the same way. If this persistence is intentional, it should be documented (as far as I can tell there is nothing in the docs that would explain this behavior, but I might have missed something). Apologies if I am mistaken or if this issue has been reported already.

Repro steps

1. AsyncStorage.setItem('someKey', 'someData');
2. Uninstall iOS app
3. Re-install iOS app
4. const data = AsyncStorage.getItem('someKey'); // returns someData

Environment

• Async Storage version: 1.9.0
• React-Native version: 0.62.2
• Platform tested: iOS 13.3

[krizzu]

Since we’re storing data in Application Support directory, it’s backed up by default.

We need a way to opt out from doing that. Going to work on that in upcoming days

[fbartho]

@Krizzu we’d be happy to try a beta build that has the final implementation of your proposed feature – I’ve commented on your PR for now with some further thoughts. This is affecting our app in production, so we’re comfortable testing an appropriate beta build in our normal QA process.