Emanuel Moecklin Emanuel Moecklin - 4 months ago 495
Android Question

Android M - check runtime permission - how to determine if the user checked "Never ask again"?

According to this: http://developer.android.com/preview/features/runtime-permissions.html#coding an app can check for runtime permissions and request permissions if it hasn't been granted already. The following dialog will be displayed then:

enter image description here

In case the user declines an important permission, imo an app should display an explanation why the permission is needed and what impact declining has. That dialog has two options: 1) re-try again (permission is requested again), 2) deny (app will work without that permission).

If the user checks "Never ask again" however, the second dialog with the explanation shouldn't be shown, especially if the user already declined once before.
Now the question is: how does my app know whether the user has checked the "Never ask again"? IMO the onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) doesn't give me that information.

A second question would be: does Google have plans to incorporate a custom message in the permission dialog that would explain why the app needs the permission? That way there would never be a second dialog which would certainly make for a better ux.

Answer

Developer Preview 2 brings some changes to how permissions are requested by the app (see also http://developer.android.com/preview/support.html#preview2-notes).

The first dialog now looks like this:

enter image description here

There's no "Never show again" check-box (unlike developer preview 1). If the user denies the permission and if the permission is essential for the app it could present another dialog to explain the reason the app asks for that permission, e.g. like this:

enter image description here

If the user declines again the app should either shut down if it absolutely needs that permission or keep running with limited functionality. If the user reconsiders (and selects re-try), the permission is requested again. This time the prompt looks like this:

enter image description here

The second time the "Never ask again" check-box is shown. If the user denies again and the check-box is ticked nothing more should happen. Whether or not the check-box is ticked can be determined by using Activity.shouldShowRequestPermissionRationale(String), e.g. like this:

if (shouldShowRequestPermissionRationale(Manifest.permission.WRITE_CONTACTS)) {...

That's what the Android documentation says (https://developer.android.com/preview/features/runtime-permissions.html#explain-need):

To help find the situations where you need to provide extra explanation, the system provides the Activity.shouldShowRequestPermissionRationale(String) method. This method returns true if the app has requested this permission previously and the user denied the request. That indicates that you should probably explain to the user why you need the permission.

If the user turned down the permission request in the past and chose the Don't ask again option in the permission request system dialog, this method returns false. The method also returns false if the device policy prohibits the app from having that permission.

To know if the user denied with "never ask again" you can check again the shouldShowRequestPermissionRationale method in your onRequestPermissionsResult when the user did not grant the permission.

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    if (requestCode == REQUEST_PERMISSION) {
        // for each permission check if the user grantet/denied them
        // you may want to group the rationale in a single dialog,
        // this is just an example
        for (int i = 0, len = permissions.length; i < len; i++) {
            String permission = permissions[i];
            if (grantResults[i] == PackageManager.PERMISSION_DENIED) {
                boolean showRationale = shouldShowRequestPermissionRationale( permission );
                if (! showRationale) {
                    // user denied flagging NEVER ASK AGAIN
                    // you can either enable some fall back,
                    // disable features of your app
                    // or open another dialog explaining
                    // again the permission and directing to
                    // the app setting
                } else if (Manifest.permission.WRITE_CONTACTS.equals(permission)) {
                    showRationale(permission, R.string.permission_denied_contacts);
                    // user denied WITHOUT never ask again
                    // this is a good place to explain the user
                    // why you need the permission and ask if he want
                    // to accept it (the rationale)
                } else if ( /* possibly check more permissions...*/ ) {
                }
            }
        }
    }
}

You can open your app setting with this code:

Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
Uri uri = Uri.fromParts("package", getPackageName(), null);
intent.setData(uri);
startActivityForResult(intent, REQUEST_PERMISSION_SETTING);

There is no way of sending the user directly to the Authorization page.