This is the toggle control in The Incident's options. If you're making a custom toggle, this is probably how you'll want to composite it - one long image with ON on the left, OFF on the right, the thumb in the middle, and a frame/mask over it.
If you do this, you HAVE to support both tapping to toggle AND sliding the thumb left-right, with the ability to cancel a slide halfway through it. Otherwise, so help me god…!
P.S. I’m reblogging this from my Dribbble page. Dribbble is a sort of Twitter/Flickr where visual artists share their images and the stories behind them. Just sayin’, there might be more of this sort of thing there.