appendix A Installing the iOS SDK In this appendix we briefly walk you through the installation of the i OS software development kit ( SDK ). A.1 Installing the iOS SDK The first step is to select and sign up for the Apple developer program and down- load the SDK . A.1.1 Becoming an Apple developer and downloading the SDK Apple frequently changes the way you can download and install Xcode. At the time of this writing, you simply have to search for "Xcode" on the Mac App Store, where you can then download Xcode 4.1 for Mac OS X Lion for free. You should always be able to find the latest version and instructions at <http:/ /developer.apple.com/ xcode/>. To get access to valuable and up-to-date developer resources you should also set up a free developer account at <http:/ /developer.apple.com/programs/