Xcode is an Integrated Development Environment (IDE) created by Apple. It provides everything you need to create apps and games for iOS. In fact, you can even use Cocos2D to create apps and games for Mac OS X, but this is not covered in this book as we're going to concentrate on making games only for iOS.
We will use Xcode throughout this book for all of our projects, so if you don't have it installed yet, you should go and install it now. Downloading and installing Xcode will take some time, as it is about 2 GB; so, don't delay this and start installing it right away.
Don't worry, it won't cost you a dime. Yes, this great IDE from Apple is completely free and you can get it easily from the Mac App Store. To install Xcode, go to the Mac App Store (don't get confused with the iTunes App Store) and search for Xcode, or alternatively, you can just visit https://developer.apple.com/xcode/downloads/ and click on View on the Mac App Store.