Of course one has to know a priori that such apps exist in order to search for them. Who in their right mind would expect to find an app that turns a phone into a flashlight?!
Actually an app is no longer needed in the current versions of iOS. That particular functionality is now built into iOS 8 and 9 and uses the LED that is intended as a "flash" for the camera. Simply swipe up from the bottom of the screen to access the
flashlight, camera, calculator, and timer. Flashlight is a frequently used function.
