Once the Quiz application is installed on your development device, return to the device’s Home screen. You’ll see that its icon is a plain white tile. Let’s give Quiz a better icon.

An application icon is a simple image that represents the application on the iOS desktop. Different devices require different sized icons, and these requirements are shown in Table 1.1.

If you supply a single application icon image at 57x57 pixels, that image will be scaled up on devices where a larger icon is required. This is never good. A scaled-up icon will be pixellated and scream, “We’re amateurs!” to your customers. Therefore, any application you deploy to the App Store should have an icon for every device class on which it can run.