If an iOS device was hacked how would you clean it?

I know that there are many ways (0-day attacks and regular vulnerabilities) iOS devices can be "hacked" remotely. Please don't put the typical line of "there is no way for an up to date iPhone to be hacked."

If you honestly think that then listen to SecurityNow podcast...there have been many 0-day remote hacks on iOS that the user doesn't even have to know about....of course all known ones have been patched but it's the unknown ones that are still out there.

I'm wondering how would one clean the iOS device of any known hack? Resetting the phone simply erases the user's data and settings correct? If the hack affected the OS then deleting the user's data and settings to reset the phone won't help. Or does doing a reset on an iOS device actually re-copy the image from storage into memory so it is truly a new image along with removing the user's data.

On a Windows device I would re-partition and then reformat the drive to reinstall the OS and clean things out...but I don't know how to do that on an iOS device.