iPhone Dev 101: Downloading and Installing the iPhone SDK

We're continuing our series of iPhone Dev 101 posts -- a TUAW feature devoted to beginning iPhone developers. I'm going to spend a little time talking about where to download and how to install the SDK. Let's first talk about what exactly an SDK is.

A software development kit is a set of tools and APIs (application programming interface) that allows a programmer the ability to develop for a specific system. Therefore, the iPhone SDK gives you the ability to program for the iPhone.

The SDK is just a waste of space on your hard drive unless you know the programming language associated with the iPhone. To program on the iPhone, you will need some Cocoa (Objective-C) knowledge. There are a ton of resources available online and in book form -- I'll cover these and more in the next post in the series. If you already know a programming language like C/C++/Java, then you should just need a refresher course on the classes, methods, and basic expressions.

To download Apple's iPhone SDK, you'll need an Apple ID -- this is a free account that you can use to access multiple Apple services including iTunes, Apple Discussions, the online store, and the developer site. If you don't have an account, you can easily get one on the iPhone Dev Center.

Continue reading to learn how to download and install the iPhone SDK.

To download the SDK:

1. Open http://developer.apple.com/iphone in your web browser. This is the iPhone Dev Center, and it offers multiple resources for the iPhone.

2. Click the "Login" button on the right-hand side of the page. Use the following pages to either login using your Apple ID, or create a new Apple ID.

3. Upon successful login, you will be returned to the Dev Center main page. Under the downloads section you should see a link to "iPhone SDK for iPhone OS 2.2." Clicking this link will start the ~1.6GB download -- the download process could take up to 3 hours (or longer) depending on your Internet connection speed.

Installing the SDK is very simple:

1. Once the download is complete, find where the .dmg file was downloaded to (normally the desktop, or User > Downloads folder). Double-click on it to open the disk image.

2. Double-click on the installer package inside of the disk image. The installer will launch and allow you to install the SDK. Just follow the on-screen instructions. Remember that installing the SDK will eat up about 2-3GBs of hard disk space; you can install the SDK on an external hard drive if necessary.

Once the installation is completed you will notice that a new "Developer" folder will be placed on the top level of your hard drive. In this folder you will find the main tools that are used to create iPhone applications. In a future iPhone Dev 101 post I'll explain what each of the applications do, and how you can use them to create your first iPhone application.

Stay tuned next week, as I'll give you some valuable Cocoa programming resources.