A Simple iOS Application - iOS Programming: The Big Nerd Ranch Guide - page 35

Application Icons

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 .

Table 1.1 Application icon sizes by device

Device Application icon size
iPhone/iPod touch without Retina display 57x57 pixels
iPhone/iPod touch with Retina display 114x114 pixels

iPad 72x72 pixels

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.

We have prepared two icon image files (sizes 57x57 and 114x114) for the Quiz application.
You can download these icons (along with resources for other chapters) from ht-
tp://www.bignerdranch.com/solutions/iOSProgramming3ed.zip . Un-
zip iOSProgramming3ed.zip and find the Icon.png and the [e-mail] files
in the Resources directory of the unzipped folder. (If you open these images, you'll see
that they aren't glossy and don't have rounded corners like other application icons. These
effects are applied for you by the OS.)

Now you're going to add these icons to your application bundle as resources . In general,
there are two kinds of files in an application: code and resources. Code (like
QuizViewController.h and QuizViewController.m ) is used to create the ap-
plication itself. Resources are things like images and sounds that are used by the applica-
tion at runtime. XIB files, which are read in at runtime, are also resources.

In the project navigator, select the Quiz project, which is at the top of the list and slightly
shaded. Then, in the editor area, select Quiz from under the Targets heading. Finally, select
Summary from the top of the editor area ( Figure 1.24 ).