2018-10-25 OC 异或校验

仅供参考,比较low

- (void) xorVerify{
      //字符串
      //转data
      //转int运算,得到结果
      NSMutableArray * m_arr = [NSMutableArray array];
    
      [m_arr addObjectsFromArray:@[@"AA",@"55",@"0F",@"02",@"83"]];
      //计算校验码
      NSMutableString * str_m = [NSMutableString string];
      int a[5];
      int j = 0;
    //字符串转成16进制
      for (NSString * hex in m_arr) {
        
          [str_m appendString:hex];
          NSData * data = [self convertHexStrToData:hex];
        
          int i = 0;
          [data getBytes: &i length: sizeof(i)];
            printf("%x\n", i); //按十六进制输出结果
            a[j] = i;
          j++;
      }
      int result = 0;
      //异或计算
      for (int i = 0; i < m_arr.count; i ++) {
          //进行16进制计算
          result = result ^ a[i];
      }
      printf("异或结果 : %x\n", result);

}

// 将十六进制字符串转换成NSData
+ (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;
}