ios 通过代码调节屏幕亮度

@interface QrCodeGenerateVC ()<UITextFieldDelegate>

{

    double currentLight;

}

- (void)viewDidLoad {

    [super viewDidLoad];

    currentLight = [[UIScreen mainScreen] brightness];

    if(currentLight < 0.65)

    {

        [[UIScreen mainScreen] setBrightness: 0.65];

    }

}

调整整个手机界面的亮度的  并不仅仅是某个app的亮度 ，要做退出页面的时候将亮度设为原来的值

- (void)viewWillDisappear:(BOOL)animated {

     [[UIScreen mainScreen] setBrightness: currentLight];

}