Now this is a seriously nifty idea:
… I thought it would be nice if we could use the front facing camera of a phone for interacting with an app. I had to see if this idea could be implemented.
Since iOS 5 Apple has added a face detection api. My idea was to detect a face and estimate the distance the device is from your face based on the size of the detected face. If the rectangle of the detected face is big, then the device is close to your face, if it’s small, then the device is far away from your face. With a similar technique it is also possible to calculate the angle of the device in relation to the face. This angle is calculated based on how fare the detected face rectangle is away from the center of the screen…
… For implementing face detection in your own application I created a class that can easily be added plus a demo project that changes the zoom level and shadow offset for a text. The only thing you have to do in your application is to add the EVFaceTracker class and listen to a deligate message so that you can react on the rectangle of the detected face.
Pretty cool, huh? Source is on github, check it out!