One of the themes of iOS 5 is PC Free, Apple’s effort to cut the proverbial iPhone cord and enable users to use their device without having to tether it back to their computer. This is a good move for a variety of reasons, and primarily because not everyone interested in an iOS device necessarily has a computer.
As a result, Apple in iOS 5 has implemented over the air system software updates. Now some of these updates can be unabashedly huge, which is why Apple has implemented delta updates whereby a user will only download portions of an updated iOS codebase that have been changed.
So just how much time and bandwidth do delta updates save?
Well, iOS 5 beta 4 is the first iOS update available as a delta update and Twitter user Hussein Hadid observes that the over the air update is 133 MB “compared to the chunky 824 MB .ipsw file.”
So overall, that’s 691 MB worth of data you won’t be downloading thanks to Apple’s new over the air updates.
Notably, some over the air updates will be available via 3G (at least that’s what the iOS SDK indicates), but these will naturally be smaller updates to keep users and carriers happy. A 150 MB update via 3G? No thanks. It’s also possible that over the air updates via 3G may be implemented on a carrier by carrier basis.
Lastly, iOS updates via 3G will only commence if a user has enough battery life remaining (some reports indicate at least a 50% charge) and at least 500 MB of available storage.