Download the iPhone SDK
The iPhone SDK and all the associated development tools are free. You can download the SDK from the following location:
Free iPhone SDK
There is a standard iPhone Developer Program that costs $99. However, you don’t need this to download the SDK and start developing.
Figure 1. The iPhone Developer Program and free iPhone SDK

Once you have registered to become an iPhone Developer, you will be able to see various links in the iPhone DevCenter.
Figure 2. The iPhone DevCenter after registration

The videos and other document links will be available with the registration.
Downloading the iPhone SDK
The prerequisites for iPhone SDK
For this version of iPhone SDK (build 9M2199a), you need the following:
- Mac OS X v10.5.3 or later
- iTunes 7.7
- iPhone OS 2.0
Figure 3. Prerequisites for iPhone development

Needless to say iPhone SDK requires Mac OS – it does not work on Windows. Obviously, it would not help Apple port all this stuff onto Windows. You can check current version of Mac OS X from Apple - About This Mac menu item.
Figure 4. The Mac Details (About This Mac)

The iPhone SDK download
The iPhone SDK is pretty big - 1.25GB. So, downloading it will take some time. The file downloaded is called iphone_sdk_final.dmg. The .dmg (Disk Image) files can be burned onto CDs and DVDs. The file extension .dmg on Macs is like .iso on Windows.
Figure 5. The iPhone SDK Download

The downloaded file will be in the Downloads directory by default. This is a disk image; and when it’s opened, it will be mounted. Once mounted, you can see the files on that disk image (just like you would see the files on a CD). After the download, all this will be done automatically.
Figure 6. Details of iPhone Disk Image

Contents of the iPhone SDK
The following are downloaded with the iPhone SDK. The figure below shows these items in Cover Flow.
- About iPhone SDK (a PDF document)
- iPhone SDK (an Installer Package)
- Packages
Figure 7. iPhone SDK download contents

The Packages directory contains several packages. Following are the packages from the build 9M2199a.
General SDKs
- Bluetooth SDK
- Core Audio SDK
- Open GL Apps
- Open GL SDK
- Other Dev Documentation
- Quick Time SDK
Developer Tools and Documentation
- CHUD
- Dev Documentation
- Developer Disk Image
- Developer Tools
- Developer Tools CLI
- Developer Tools System Support
- Dev Examples
- Dev SDK
- Dev Tools Documentation
- Distribute Builds Support
- XCode3 xExtras
- Versioned Developer Tools System Support
GNU Compilers
- GCC 3.3
- GCC 3.3 ADC Docs
- GCC 4.0
- GCC 4.0 ADC Docs
- GCC 4.2
- GCC 4.2 ADC Docs
- llvm-gcc 4.2
iPhone Developer Tools
- iPhone Documentation
- iPhone Host Side Tools
- iPhone SDK Headers and Libs
- iPhone Simulator Platform
- iPhone System Components
Java SDK
Operating System Related
- Mac OS X 10.4 Universal
- Mac OS X 10.5
- Relocatable Script
- System Script
- X11 Documentation
- X11 SDK
Web Kit and Web Objects
- Web Kit SDK
- Web Objects
- Web Objects Development
- Web Objects Documentation
- Web Objects Examples
- Web Objects Runtime
Installing the iPhone SDK
The following article shows the details of installing iPhone SDK
Installing the iPhone SDK