A launch image matching the device resolution appears as soon as the user taps your app icon and while your app is launching. Use screenshots to create your app’s launch images. To take advantage of Retina displays, provide high-resolution images for each device you support.
For guidance on creating launch images, see the Application Icons and Launch Images for iOS sample code. For the sizes of all required app icons, launch images, and other icons, refer to the respective platform human interface guidelines.