When you develop apps, you use the iOS software development kit (SDK) and Xcode, Apple’s integrated development environment (IDE). Xcode provides everything you need to create great apps for iPhone, iPod touch, and iPad. It includes a source editor, a graphical user interface editor, and many other features—from customizable builds to source repository management. Xcode employs a single window, called the workspace window, that holds most of the data you need. With Xcode, you smoothly transition from writing code, to debugging, to designing your user interface, all within the same window. The iOS SDK extends the Xcode toolset to include the tools, compilers, and frameworks you need specifically for iOS.
To get started, you need to:
Download the latest version of Xcode.
Open the Mac App Store app on your Mac, search for Xcode, and click Free to download Xcode. When you download Xcode, the iOS SDK is included. (The Mac App Store app is installed with Mac OS X version 10.7 and later. If you have an earlier version of Mac OS X, you need to upgrade.)
Enroll as an Apple Developer in the iOS Developer Program.
You do not need to enroll in the program to write apps and test them in Simulator. You do need to enroll, however, to test apps on devices and to distribute apps. Enrollment gives you full access to the iOS Dev Center and the iOS Provisioning Portal. If you enroll now, you will be able to follow all of the steps in the road map, including testing your app on a device.