Xcode

The first thing we need to do is install Xcode. This is the environment used by developers working in Objective-C to build their Mac OS X and iPhone applications.

The latest version is 4, which is free for developers, but there is a $99 charge for that status.
Alternatively, you can pay $4.99 on the iTunes store.
What I'm using is Xcode version 3, which is free and can be found at the bottom right of this website. You may need to sign up for a developer account, but there is no immediate charge for this:

http://developer.apple.com/xcode/

Download Xcode and follow the installation instructions. Then we can begin learning Objective-C!