// 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];

                }

            }