UILaunchImageName
A string containing the name of the image file.
Discussion
The image file must reside at the top level of the app bundle. The name you specify for this key should not include a filename extension, nor should it include modifiers such as @2x, -568h, ~iphone, or ~ipad.
On disk, your image filenames may still include the modifiers as appropriate, although they are not required. The system automatically considers such modifiers when choosing which file to load.