The much anticipated iPhone OS 4 or iOS 4 has been officially released recently and existing users can actually upgrade to the latest OS via their devices (iPhone and iPod touch) for free. There are two main method of how to download and upgrade to the latest version and I’m going to share these two methods:

Upgrade Method 1

1. Install the latest iTunes 9.2 on your PC or Mac and launch it.
2. Then connect your iPhone or iPod Touch to the PC or Mac.
3. Select your Device from the Sidebar of iTunes. You will see summary page with an option for update. But don’t upgrade yet.
4. Right click on the device icon in the sidebar of iTunes and back it up. Just in case unwanted incident or upgrade failure happens.
5. After done backing up, go back to Step 3 and click on “Check for Update”. And you will be guided on the upgrading process.

Upgrade Method 2

1. This is to be done manually.
2. Download the update file according to your iPhone or iPod Model from below:

• Download iOS 4 for iPhone 3GS (378 MB)
• Download iOS 4 for iPhone 3G (292 MB)
• Download iOS 4 for iPod Touch 3G (366 MB)
• Download iOS 4 for iPod Touch 2G (315 MB)

1. Then launch iTunes 9.2 and connect your device. As in method 1, backup your device (Step 3 and 4)
2. Click the Update button while holding the Shift key (in Windows) and Option key (on Mac).
3. Browse to the iOS 4 firmware location (that you have downloaded) and choose the Open option to proceed
4. The update process will begin.

Well, upgrade now and enjoy the new features.