16进制颜色(html颜色值)字符串转为UIColor

互联网 App 中经常会用到 html 颜色值转换 UIColor，比如：#FF9900、0XFF9900 等颜色字符串，以下方法可以将这些字符串转换为 UIColor 对象。

    + (UIColor *) colorWithHexString: (NSString *) stringToConvert

    {

     NSString *cString = [[stringToConvert stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

     

     // String should be 6 or 8 characters

     if ([cString length] < 6) return DEFAULT_VOID_COLOR;

     

     // strip 0X if it appears

     if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2];

     f ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];

     if ([cString length] != 6) return DEFAULT_VOID_COLOR;

     // Separate into r, g, b substrings

     NSRange range;

     range.location = 0;

     range.length = 2;

     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];

    }