The introduction of iPad creates new opportunities for application development using iOS. Because it runs iOS, an iPad is capable of running all of the same applications already being written for iPhone and iPod touch. However, the larger screen size of iPad also means that there are now new opportunities for you to create applications that go beyond what you might have done previously.

This document introduces the new features available for iPad and shows you how to use those features in your applications. However, just because a feature is available does not mean that you have to use it. As a result, this document also provides guidance about when and how you might want to use any new features in order to help you create compelling applications for your users.

The iPhone SDK provides the tools and resources needed to create native iPhone applications that appear as icons on the user’s Home screen. Unlike a web application, which runs in Safari, a native application runs directly as a standalone executable on an iPhone OS–based device. Native applications have access to all the features that make the iPhone and iPod touch interesting, such as the accelerometers, location service, and Multi-Touch interface. They can also save data to the local file system and even communicate with other installed applications through custom URL schemes.

In iPhone OS, you develop native applications using the UIKit framework. This framework provides fundamental infrastructure and default behavior that makes it possible to create a functional application in a matter of minutes. Even though the UIKit framework (and other frameworks on the system) provide a significant amount of default behavior, they also provide hooks that you can use to customize and extend that behavior.