How Do We Distinguish Never-Asked From Stop-Asking in Android M's Runtime Permissions?

Question

When it comes to the M Developer Preview runtime permissions, according to Google:

1. If you have never asked for a certain permission before, just ask for it<

Answer 1

As per the current example: https://github.com/googlesamples/android-RuntimePermissions/blob/master/Application/src/main/java/com/example/android/system/runtimepermissions/MainActivity.java#L195

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions,
        int[] grantResults) {
    if (requestCode == REQUEST_CAMERA) {
        if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            doThing();
            //STORE FALSE IN SHAREDPREFERENCES
        } else {
            //STORE TRUE IN SHAREDPREFERENCES
        }
    }

Store a boolean in SharedPreferences with key as your permission code and value as indicated above, to indicate whether that preference has been denied before.

Sadly, you probably can't check against a preference that has been accepted and later denied while your app is running. The final spec is not available, but there's a chance that your app either gets restarted or gets mock values until the next launch.