See: The i OS 8 update can be installed on the i Phone 5S, i Phone 5C, i Phone 5, i Phone 4S, i Pad Air, i Pad mini Retina, i Pad mini, i Pad 4, i Pad 3, i Pad 2, and i Pod touch 5. Tap on the available update and hit Install—all you'll need is a strong Wi-Fi connection.But, given Apple's previous history with server overloads and millions of people downloading the update at the same time, it's always more reliable to update via i Tunes.
Now find the IPSW file you just download and select it.
If you downloaded and installed the Gold Master build of i OS 8, then you're already running the same version that was released to the public.
Since i OS 8 promises to pack a bunch of new, really great features, it's time to present your options for getting on the latest and greatest for your Apple device.
There are two ways to update your system, just make sure that your device has at least 50% battery and that you've cleared plenty of storage space—you'll need anywhere from 3 to 7GB free, depending on device.
Below, the guide is divided into two sections: The regular, public updates (the official launches) and the beta updates (the ones you have to sign up to get before anyone else).