在已知UIColor的情况下，获取器RGB的值

在网上找了几个方法，都不是很有用在这里分享下一个方法

- (void)getRGBComponents:(CGFloat [3])components forColor:(UIColor *)color {
    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
    unsigned char resultingPixel[4];
    CGContextRef context = CGBitmapContextCreate(&resultingPixel,
                                                 1,
                                                 1,
                                                 8,
                                                 4,
                                                 rgbColorSpace,
                                                 (CGBitmapInfo)kCGImageAlphaNoneSkipLast);

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, CGRectMake(0, 0, 1, 1));
    CGContextRelease(context);
    CGColorSpaceRelease(rgbColorSpace);
    for (int component = 0; component < 4; component++) {
        components[component] = resultingPixel[component] / 255.0f;
    }
}

//调用
CGFloat components[4]; 
[self getRGBComponents:components forColor:color];
NSLog(@"%f %f %f", components[0], components[1], components[2]);