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我正在 iOS 中开发一个聊天程序。但我无法解决与线程相关的问题。首先，我创建了一个服务器套接字来处理线程中的多个连接。我的代码是这样的：

    - (void)viewDidLoad
    {
        [super viewDidLoad];

        [NSThread detachNewThreadSelector:@selector(aMethod:) toTarget:[self class] withObject:nil];
    }

    void doprocessing(int sock)
    {
       int n;

       char *buffer = malloc(256);

       bzero(buffer,256);

       n = read(sock,buffer,255);
       if (n < 0)
       {
          perror("ERROR reading from socket");
          exit(1);
       }

      printf("Here is the message: %s\n",buffer);

      n = write(sock,"I got your message",18);

      if (n < 0)
      {
         perror("ERROR writing to socket");
         exit(1);
      }
   }

   +(void)aMethod:(id)param{

    int x;
    for(x=0;x<50;++x)
    {
    int sockfd, newsockfd, portno, clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int  n;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
    {
        perror("ERROR opening socket");
        exit(1);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = 5001;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *) &serv_addr,
             sizeof(serv_addr)) < 0)
    {
        perror("ERROR on binding");
        exit(1);
    }

    listen(sockfd,5);
    clilen = sizeof(cli_addr);
    while (1)
    {
        newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr, &clilen);
        if (newsockfd < 0)
        {
            perror("ERROR on accept");
            exit(1);
        }

        int pid = fork();
        if (pid < 0)
        {
            perror("ERROR on fork");
            exit(1);
        }
        if (pid == 0)
        {

            close(sockfd);
            doprocessing(newsockfd);
            exit(0);
        }
        else
        {
            close(newsockfd);
        }
        } 
    }
}

如您所知，我无法访问该线程中的 gui 元素。出于这个原因，我调用了 mainThread 函数，但仍然无法访问 gui 元素。我得到了这个结果：

The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec().
Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.

如果我不使用叉子，它可以工作。但我的问题是，我怎样才能通过使用 fork 函数来访问 gui 元素？

4

1 回答 1

2

（正如您在评论中所说，这是针对越狱设备的，否则您根本无法使用 fork() 或 exec() 。）

您遇到了 Apple 框架的限制，该限制记录在技术说明 TN2083“守护程序和代理”中的过时编程技术中：

守护框架

如果您调用 fork 但不调用 exec，许多 Mac OS X 框架将无法可靠运行。唯一的例外是 System 框架，即使在那里，POSIX 标准也严格限制了您在 fork 和 exec 之间可以做什么。

于 2013-04-08T06:04:46.040 回答