For iPhones, is there a good photoshop app?

I mean one where I can photoshop a face from one pic to another.

And I'm not talking about a one way street where the app chooses which body or face for me, but one where I get to choose the body AND face straight from my camera roll. And please don't suggest artstudio because it does not work.

Adobe photoshop express on the App Store for iPhone. Also an app called cut me in.