ios - THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY

Question

我正在 iOS 中开发一个聊天程序。但是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，在一个线程中处理多个连接。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。为此，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 fork，它就可以工作。但我的问题是如何使用 fork 函数访问 gui 元素？

Answer 1

(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 框架的限制记录在 Obsolete Programming Techniques 中在技​​术说明 TN2083“守护进程和代理”中:

Daemonizing Frameworks

Many Mac OS X frameworks do not work reliably if you call fork but do not call exec. The only exception is the System framework and, even there, the POSIX standard places severe constraints on what you can do between a fork and an exec.