Sure, any application can have one. But the real question is, should it have one? And the iOS Human Interface Guidelines (as mentioned earlier), suggest that no, it shouldn't have this ability.
That said, you will have to manage the game's state when the user switches to another app, turns off the phone, or it just dies. Obviously you don't want to touch and resume a game, and have it throw you directly into active gameplay.
My own approach would be to detect when the game is no longer active, and then to have it automatically pause the game, complete with a "Game paused, touch to continue" prompt on screen.
I also would spend a lot of time checking out iOS apps and games that were similar to what I had in mind, and look at how they handle this case. I think you'll find few (if any) apps have an explicit "quit" option which ought to tell you a) what users are used to, and b) what makes an app fit Apple's acceptance standards.