Programming iOS 6, 3rd Edition

Device Architecture and Conditional Code

As you create a project (File → New → Project), after you pick a project template, in the screen where you name your project, the Devices pop-up menu offers a choice of iPad, iPhone, or Universal (meaning an app that runs on both iPhone and iPad natively, typically with a different interface on each type of device).

You are not tied forever to your initial decision, but your life will be simpler if you decide correctly from the outset. The iPhone and iPad differ in their physical characteristics as well as their programming interfaces. The iPad has a larger screen size, along with some built-in interface features that don’t exist on the iPhone, such as split views and popovers (Chapter 22); thus an iPad project’s nib files and some other resources will typically differ from those of an iPhone project.

Your choice in the Devices pop-up menu affects the details of the template on which your new project will be based. It also affects your project’s Targeted Device Family build setting:

iPad

The app will run only on an iPad.

iPhone

The app will run on an iPhone or iPod touch; it can also run on an iPad, but not as a native iPad app (it runs in a reduced enlargeable window, which I call the iPhone Emulator; Apple sometimes refers to this as “compatibility mode”).

iPhone/iPad

The app will run natively on both kinds of device, and should be structured as a universal app.

Two additional build settings determine what systems your device will run ...