(Android 11) How do I allow an app to access a file in another app's Android/data folder?

Question

I have two apps. One app (P) consumes a file with a proprietary extension (say.XXX) and a.json file with instructions for what P will be doing with that other file. The other app (Q) creates those files and intents to P, telling P the path to the.json file, which contains the path to the.XXX file. P then reads the.json file (in Q's directory) and then reads the.XXX file (again, in Q's directory). P does a lot of stuff with the.XXX file, but I don't believe P has to write to it.

Prior to Android 11, all the files were just in root/MyAppDirectory_Q and it was easy to access/share files between apps. With scoped storage getting more popular, I need to keep all files in the Android/data/com.companyName.MyApp_Q directory.

How do I intent from Q to P and give P the permissions to access the two files in Q's Android/data folder? I'm doing this in Xamarin, but I'll eventually have to recreate Q in straight Java once it's working.

Answer 1

One approach is for Q to send a broadcast to P with URIs in the Intent (using ClipData). Q will grant persistable permission using FLAG_GRANT_PERSISTABLE_URI_PERMISSION and grantUriPermission() . P will receive the broadcast with the URIs and accept them using takePersistableUriPermission() . After that, P will be able to access the files using the URIs provided. The URIs may come from FileProvider, so they are backed by the files in Q's external files directory.