That isn't how that word is normally used, AFAIK? Even most "persistent" attacks are thwarted by device updates on iOS; to get persistence through an update tha

That isn't how that word is normally used, AFAIK? Even most "persistent" attacks are thwarted by device updates on iOS; to get persistence through an update that fixes the underlying exploit you are using would involve messing with the update mechanism itself and refusing to update at least that part and then like, trying to simulate the update to look like it was still updated... and due to how Apple's software architecture tends to assume everything is updated at once, trying to show the user a new userland (what the user will experience) but with an old kernel (a prerequisite to maintain access if your bugs came in userland as otherwise the new kernel will refuse to run the old exploitable code)--particularly as your attack might not give you the ability to modify much kernel behavior--is actually quite difficult. (Also, the firmware update process on iOS has different ways of being kicked off: if you do it over USB from iTunes, you might not have an opportunity to mess with the process at all.)