检出屏幕亮度

检测当前屏幕亮度：

ASCScreenBrightnessDetector *brightnessDetector = [ASCScreenBrightnessDetector new];
NSLog(@"Screen brightness: %f", brightnessDetector.screenBrightness);
ASCScreenBrightnessStyle style = brightnessDetector.screenBrightnessStyle; 
switch (style) { 
case ASCScreenBrightnessStyleDark: 
    // Do something, e.g. set a dark theme. 
    break; 
case ASCScreenBrightnessStyleLight: 
    // Do something else, e.g set a light theme. 
    break; 
} 

响应屏幕亮度变化的delegate函数：

- (void)screenBrightnessDidChange:  (CGFloat)brightness 
{ 
NSLog(@"The new brightness is: %f", brightness);
 } 

- (void)screenBrightnessStyleDidChange:(ASCScreenBrightnessStyle)style 
{ 
NSLog(@"The new style is: %u", style); 
}