How do i save apps without backing them up
I want to factory restore my ipod like i just bought it without havin to restore from a back up that is most likely causing me issues with corrupt files in it i wan to start from scratch but save one app that is no longer on the app store us market how do i save tha individual app somewhere with nothing else to later out on my ipod the rest i can install myself
iPod touch, iOS 6.1.5