iOS 7 adds a very interesting feature “Switch Control” which allows you to control your device with head gestures. To use Switch Control, just go to Settings -> General -> Accessibility -> Switch Control, turn it on. You can also triple-click Home button to enable or disable it.
Switch Control allows you to use your iPhone by sequentially highlighting items on the screen that can be activated through an adaptive accessory.
Once Switch Control enabled, it will scan your face through the front camera, then the cursor will loop select all Items on your screen, you can open or exit any item through the head motion. The feature was originally designed for those people who are physically challenged, but now the experience is rather poor, expected to improve further.
Any case, it is a good innovation, here to teach you how to use the “Switch Control” through a Youtube video from technobuffalo.