InfinitLight

InfinitLight is the simplest way to use your iPhone 4 as a flashlight by using the camera's flash on the back. It also works on other devices by turning the screen white, which can be surprisingly effective in a dark place.

It was designed to prevent accidental input on the screen from disabling the light emission. As such, there is no button to turn the light on and off, no strobe mode, etc. Instead, just quit using the Home button or suspend using the Sleep button to turn the light off.

Also for this reason, there are no ads displayed on the screen — tapping them could affect the use of the app as a flashlight.

Finally, while InfinitLight is running, the phone is kept from going into sleep mode after a period of time to ensure the light stays lit. The status bar remains visible so that battery level and other information can be monitored during this time, though.

When used on an iPhone 4, the screen is darkened with a dark texture and an icon is displayed in the corner which corresponds to the position of the light on the back of the device.

Note: Use of the camera flash for extended periods of time can severely decrease battery life.