NSRange rangeErr;

        rangeErr.location = 6;

        rangeErr.length = 2;

        NSString *strings = [value substringWithRange:rangeErr];

        int errCode = (int)strtoul([strings UTF8String],0,16);  //16进制字符串转换成int

        NSString *ascStr = [NSString stringWithFormat:@"%c",red];

iOS 16进制字符串转换成int十进制