iOS 获取、设置屏幕亮度

获取当前屏幕的亮度
CGFloat lightValue = [UIScreen mainScreen].brightness;

//设置亮度大小 设置范围：0.1 -1.0
[[UIScreen mainScreen] setBrightness:0.6];

//设置屏幕常亮
[UIApplication sharedApplication].idleTimerDisabled = YES;