Unless you have extremely sensitive information, I'd just follow these directions:
http://support.apple.com/kb/ht2110
Unless you have extremely sensitive information, I'd just follow these directions:
http://support.apple.com/kb/ht2110
That only deletes the data, but doesn't erase it.
If you want to FULLY erase the data, use a program to do it.
That's correct on the newer devices (per the article, it did an overwrite on the older devices -- the newest thing I've personally done this on is an original iPhone).
Like I said... figure out how much is at risk. If you just don't want your personal info in other people's hands, the hardware encryption key technique is probably fine. If you stored something really sensitive, that could get you in legal trouble, like HIPAA-covered medical records or trade secrets, consider some more aggressive caution.
BTW do you have a program for doing multiple random overwrites that you recommend?
Well there are programs that can do it, but you will need to access the filesystem (make the iPhone act like a HDD) to do it:
http://www.heidi.ie/eraser/
http://www.piriform.com/ccleaner For mac: http://www.piriform.com/mac/ccleaner
..I've sold 2 iPads and 5 iPhones and erased them all using that method, and never had a problem. ...