Change Backlight Brightness on iPhone Programmatically

Question

Does the SDK provide any way to change the brightness of the backlight, or turn it off temporarily?

Answer 1

In my SDK (5.0.1) it seems that "GraphicsServices.h" is no longer there, but you can declare it yourself like this:

void GSEventSetBacklightLevel(float level);

Note that the linker will complain, unless you include the framework GraphicsServices.framework in your project.

About your question about turning the backlight off, I found out that you can do it by passing a very large negative number to GSEventSetBacklightLevel, like this:

GSEventSetBacklightLevel(-INFINITY);

In my tests this will completely black out the screen.

Remember that this might still cause burn-in in the LCD pixels if you display static graphics, even when the backlight is off. And that this call will cause rejection if submitteed to app store.