Question

Is it possible to reduce light(brightness) of screen from code ?

Answer 1

This is not a “published” API, therefore Apple will reject your sumbission from the App Store if you use it. So the short answer is “No”.

However…

An effective technique that people use is to place a UIView over your main window, give it a solid black background, then adjust the opacity to darken what shows behind it. I’ve done this by doing the following:

In your appDelagate’s “applicationDidFinishLaunching” call, where you would normally do:

[window addSubview:viewController.view];

Instead do:

[window addSubview:viewController.view];
[window addSubview:darkScreen];

Where “darkscreen” is an (IBOutlet) UIView created with Interface builder and in the MainWindow.xib as follows:

1. Background is BLACK
2. Alpha is 0
3. User interaction is disabled

When you want to “dim” the screen, reference darkScreen from your appDelegate, and bump up it’s Alpha.