ios 10进制转16进制

-(NSString *) toHex:(long long int)num
{
    NSString * result = [NSString stringWithFormat:@"%llx",num];
    return [result uppercaseString];
}

      NSString *hex=[self toHex:[head.codeId intValue]];
      unsigned long red = strtoul([hex UTF8String],0,16);

      NSLog(@"转换完的数字为：%lx",red);

16进制字符串转NSdata

//每两个字节转一次
+ (NSData *)convertHexStrToData:(NSString *)str {
    if (!str || [str length] == 0) {
        return nil;
    }

    NSMutableData *hexData = [[NSMutableData alloc] initWithCapacity:8];
    NSRange range;
    if ([str length] % 2 == 0) {
        range = NSMakeRange(0, 2);
    } else {
        range = NSMakeRange(0, 1);
    }
    for (NSInteger i = range.location; i < [str length]; i += 2) {
        unsigned int anInt;
        NSString *hexCharStr = [str substringWithRange:range];
        NSScanner *scanner = [[NSScanner alloc] initWithString:hexCharStr];

        [scanner scanHexInt:&anInt];
        NSData *entity = [[NSData alloc] initWithBytes:&anInt length:1];
        [hexData appendData:entity];

        range.location += range.length;
        range.length = 2;
    }
    return hexData;
}