IPhone – Long time for resetting procedure in iPhone 6

I've had an iPhone 4 since the day it came out. After the first year or so the oleophobic property has completely gone: it's now no different to my old iPhone 3G screen in terms of finger smears. I've never cleaned it with any sort of chemical agent but I've also never kept it in a case that covers the screen, and it spends a lot of time in my jeans pocket. So the answer is yes, under some conditions it certainly does wear off over time. Your mileage may vary, of course: kept in a case, or carried in a bag or purse where the screen doesn't get rubbed, it should last much longer.

If you have a recent backup (and thus aren't afraid of doing a fresh install and restore), there are a few things to try - all of them involve putting the phone in a mode that makes iTunes prompt you to do a complete restore/update/sync afresh.

• Put the phone in Recovery Mode, and restore it.

If that doesn't help:

• Try putting the phone in DFU mode and restoring it.
• If you find the above instructions difficult to follow, especially with the timing between actions
  • just download redsn0w (look for the download links at the bottom of the blog post)
  • run redsn0w
  • go to the DFU option
  • it will guide you step-by-step to put the phone in DFU mode
  • once that's done, restore it from iTunes. Although redsn0w is primarily meant for jailbreaking, it is very useful for putting a phone in DFU mode.