Here’s a nice example from Danny Shmueli showing how to use the facial gesture recognition on streaming video added with iOS 7 for detecting blinking, and smiling gestures.
One of the key issues with using this facial gesture recognition feature is that performance, and the example does a nice job of handling this issue. The logic has been nicely extracted so you can use this gesture recognition in your own projects.
Here’s a video showing DSFacialGestureDetector in action:
You can find DSFacialGestureDetector on Github here.