It's possible to use showsCameraControls = YES; and avoid the overlay on the preview view. I had the same problem and could solve it by using NSNotificationCenter along with @"_UIImagePickerControllerUserDidCaptureItem" and @"_UIImagePickerControllerUserDidRejectItem".
When entering the preview view you can remove the overlay :) A working code example can be found here: https://stackoverflow.com/a/23899448/1933185