Download and install iPhone/iPad SDK
If you want to start developing for the iPhone, iPod Touch, or iPad, the first thing you’ll need to do is download and install the iPhone SDK. Yes, the iPhone SDK is what you will want to download even if you have no intention on developing for the iPhone itself and only the iPad, they both run the same iPhone OS operating system.
You will need your Apple user ID, this is the same login you use when you access iTunes, register an Apple product, use the Apple forums, and for other communication with Apple.
Downloading the iPhone SDK
* Go to http://developer.apple.com/iphone
* Enter your Apple login ID information and login
* Once you are logged into the iPhone Development Center, look for the ‘Downloads’ link for iPhone SDK, it is usually bundled with Xcode and will be labeled something like “Xcode 3.2.2 and iPhone SDK 3.2″, the combined download size of the iPhone SDK and Xcode is about 2.3 GB, and takes about 6.5GB of hard drive space to install.
Installing the iPhone SDK
* Once the file is finished downloading, launch the installer and follow the onscreen installation instructions. Remember that a sizable amount of disk space will be used to install Xcode and iPhone SDK.
* After the installation is complete, you will have a new directory located at the root of your Mac called ‘Developer’, inside this directory will be developer apps, tools, resources, the iPhone simulator, and more.
What’s next? Books? Sample code?
If you’re new to iPhone and iPad development, picking up a good book on the topic is a pretty good idea. Beginning iPhone 3 Development: Exploring the iPhone SDK is a popular choice on Amazon and is a good starting point.
Another good resource is the iPhone OS reference library on Apple.com, there’s plenty of code samples and other helpful information. Apple’s iPhone Human Interface Guidelines is a helpful read too when working on an interface for your app.