Live Face detection ImagePicker for iPad
Very easy-to-use and can be easily customised. Purely written in obejct-c, no OPENCV at all!
It will trigger the camera u defined (front or back), and detect the people's face in the camera. If people's face is detected, it will take photo and return the photo data back.
I wrote this control for a commercial project which has been used millions of times per day all around the world. So it is very reliable.