Something fishy and mysterious in the bahama login app

something fishy and mysterious in the bahama login app. i cannot see any constraints or autolayout in the app and still the app is working fine in all screen sizes. i even commented out the UI initialization code in view did load still its working like charm. how is that possible ???
and this animation is working fine in your starter project but not in any other project. when i tried to implement this animation in my app it moves from centre of the screen to right side of the screen instead of moving from left side to centre of the screen. any suggestions ?