IOS 颜色转换

颜色转换一：透明度固定为1，以0x开头的十六进制转换成的颜色

+ (UIColor*) colorWithHex:(long)hexColor{
return [UIColor colorWithHex:hexColor alpha:1.0];
}

颜色转换二： 0x开头的十六进制转换成的颜色,透明度可调整

+ (UIColor *)colorWithHex:(long)hexColor alpha:(float)opacity{
float red = ((float)((hexColor & 0xFF0000) >> 16))/255.0;
float green = ((float)((hexColor & 0xFF00) >> 8))/255.0;
float blue = ((float)(hexColor & 0xFF))/255.0;
return [UIColor colorWithRed:red green:green blue:blue alpha:opacity];
}

颜色转换三：iOS中十六进制的颜色（以#开头）转换为UIColor

+ (UIColor *) colorWithHexString: (NSString *)color {
    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet     whitespaceAndNewlineCharacterSet]] uppercaseString];

    // String should be 6 or 8 characters
    if ([cString length] < 6) {
        return [UIColor clearColor];
    }

    // 判断前缀并剪切掉
    if ([cString hasPrefix:@"0X"])
        cString = [cString substringFromIndex:2];
    if ([cString hasPrefix:@"#"])
        cString = [cString substringFromIndex:1];
    if ([cString length] != 6)
        return [UIColor clearColor];

    // 从六位数值中找到RGB对应的位数并转换
    NSRange range;
    range.location = 0;
    range.length = 2;

    //R、G、B
    NSString *rString = [cString substringWithRange:range];

    range.location = 2;
   NSString *gString = [cString substringWithRange:range];

    range.location = 4;
    NSString *bString = [cString substringWithRange:range];

    // Scan values
     unsigned int r, g, b;
    [[NSScanner scannerWithString:rString] scanHexInt:&r];
    [[NSScanner scannerWithString:gString] scanHexInt:&g];
    [[NSScanner scannerWithString:bString] scanHexInt:&b];

    return [UIColor colorWithRed:((float) r / 255.0f) green:((float) g / 255.0f) blue:((float) b / 255.0f) alpha:1.0f];
}