If you’re a registered developer with Apple ($99/year), you can download and install pre-release software, including new versions of iOS for your iPhone, iPod, or iPad. There are a few steps you need to do in order to be able to install this software on your devices.
Activating Your Account
The first step after paying for your subscription is activating your account. After you go through the setup process, you’ll be emailed an activation code within 24 hours (usually within a couple of hours). You can click on the link in your email and enter the activation code to make your developer account live.
Register Your Device
In order to install pre-release software onto your device, you need to register it with your developer account. To go the iOS Dev Center and login.
Then click on the Certificates, Identifiers & Profiles link in the right column. Then click on Devices under iOS. Click on the + button to add a new device. You can add up to 100 devices with a standard account.
You’ll need to find your UDID (Unique Device Identifier) to register your device. This is a string of 40 characters unique to every device. There are two ways you can get your UDID. The first is to install the Ad Hoc Helper onto your device, which will create an email you can send to yourself.
The other way is to use iTunes. Connect your phone to your computer and open up iTunes and go to your device summary. On that screen, click on the serial number for your device and it’ll show you your UDID.
Download & Extract The Beta Software
Back in the iOS Dev Center, you’ll want to look for the beta version of iOS you want to install. Make sure you read their Read Me warning about selecting the right software for your device (GSM vs CDMA). Then you’ll download the .dmg package, which is made for a Mac, but download it anyway.
After the file is downloaded, you’ll need a program like 7-Zip to extract it. Open up the .dmg file in 7-Zip and open the 2.hfs folder within 7-Zip and look for the .ipsw file. You’ll want to extract that to your computer and remember the file location because this is what we’ll be using to restore your device.
Backup & Restore
After the .ipsw file is extracted, you’ll want to connect your phone to iTunes and do a full backup to your computer. After that, you’ll want to hold down the Shift key and click on the Restore button within iTunes. This will open a browser window which will let you select the .ipsw file you extracted. Once you do that, follow the prompts, your device will reboot a couple of times and you’ll have the latest iOS beta on your device.
After the install, everything will be fresh on your phone. From there, you can select to restore your files within iTunes or you can just start from scratch.