Check if user allowed to add the photo library

Hi!

In my photo app the user can save the photos he took to iOS “Photos”. So the NSPhotoLibraryAddUsageDescription will say: “This app would like to add the photo library.” 

How can I check if the user denied the access in order to warn him, that all his photos will be deleted if he continues?
I tried it with
[lua]local hasLibrary,hasAccessToPhotos= media.hasSource( media.SavedPhotosAlbum )[/lua]

But both variables are always true.

Maybe someone has an idea. Thank you very much.
 

Tim