修改屏幕亮度

  // 手滑动左边部分修改的是亮度
            if ((firstPoint.y - secondPoint.y) > 0) {
               
                // 增加亮度
                if ([UIScreen mainScreen].brightness < 1.0) {
                    [[UIScreen mainScreen] setBrightness:[UIScreen mainScreen].brightness = [UIScreen mainScreen].brightness + 0.025];
                }
            }else {
                // 降低亮度
                if ([UIScreen mainScreen].brightness > 0.0) {
                    [[UIScreen mainScreen] setBrightness:[UIScreen mainScreen].brightness = [UIScreen mainScreen].brightness - 0.025];
                }

            }