How to require different permissions in annotation depending on Android version

I have a function in a custom library that requires the BLUETOOTH_SCAN and BLUETOOTH_CONNECT permissions. Starting with Android 12, I can't just rely on adding them to the manifest XML - runtime checks are also required then.

I added the RequiresPermission annotation to my function, like this:

@RequiresPermission(allOf = [Manifest.permission.BLUETOOTH_SCAN, Manifest.permission.BLUETOOTH_CONNECT])
fun myFunction()

However, I get this warning:

Field requires API level 31 (current min is 28): android.Manifest.permission#BLUETOOTH_SCAN

I set the min SDK version to 28 on purpose. But now I am stuck. for Android 12 and newer, I need the annotation to emphasize that callers check for those permissions (in other words, I want there to be a warning if callers use my function without a permission check). for Android 11 and older, the annotation must not be present? How do I solve this? I know that RequiresPermission has a conditional argument, but I do not know how to use this for this purpose. I tried to instead use BLUETOOTH and BLUETOOTH_ADMIN permissions in the annotation, but Android Studio still complains that the Bluetooth APIs that are internally used in the function need to be surrounded by permission checks.

Solution

You could annotate android version like the following (for example only, this is a different permission request)

    @RequiresApi(api = Build.VERSION_CODES.TIRAMISU)
    @RequiresPermission(allOf = {Manifest.permission.POST_NOTIFICATIONS})

Although I find it easier to read and debug later by having all versions call the request permission function then return early if the version is too low

if (Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU) {
  return
}
//continue to ask for permission