In order to enhance the user experience of your application, Apple requires your application to include a launch image. Basically, a launch image is an image of what your application looks like when it is loaded for the first time. Using a launch image ensures that while your application is being loaded, the user is not staring at a blank screen. Instead, the launch image is displayed. This engages the user with your application immediately. When it is fully loaded, the launch image then disappears, and your application displays its first screen, ready to use.
Creating a launch image is simple — you merely create a file named Default.png and save it in the application bundle (i.e., in your project, such as the Supporting Files folder). This image needs to have a resolution of 480X320 pixels (or 960X640 for iPhone's Retina display). When your application is loaded, the system will automatically display this image and then hide it when the first View window of your application is ready to be shown. If you want to display different launch images depending on the resolution of the device, you can do the following: