These startup images are used by iPhone and iPad apps that are installed to the
home screen. These images are displayed before the splash screen is displayed.

If you want to create a new splash screen, it is recommended that you start by
modifying the files in the adjacent "splash" folder, then take screenshots of
device, crop, and save into this directory. This is the best way to avoid visual
artifacts when the app transitions from the Apple startup images to the splash
screen assets.