Compatible with iOS 7 and 8
"Camera Proximity Snap", the feature introduced in some Android smartphones, now this feature is also available for your iPhone, for free. :)
This tweak allows you to take photos using the proximity sensor, by moving your hand over and near the sensor. (In an another word, if the sensor detects the motion, for a convenient interval) No need to tap the shutter button or press the volume button to take photos.
Configure from Settings.