Stdout redirection not working in iOS without debugger

问题

I am trying to redirect output so I can send it over the network. For some reason if you run the code while debugger attached it works perfectly. Once you start the application in normal way the code freezes on the read function and never returns. If someone has any pointers I will highly appreciate it.

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^(void) {
            static int pipePair[2];
            if ( pipe(pipePair) != 0) {
                return;
            }
            dup2(pipePair[1],STDOUT_FILENO);
            while (true) {
                char * buffer = calloc(sizeof(char), 1024);
                ssize_t readCount = read(pipePair[0],buffer,1023);
                if (readCount > 0) {
                    buffer[readCount] = 0;
                    NSString * log = [NSString stringWithCString:buffer encoding:NSUTF8StringEncoding];
                    //sent it over network
                }

                if (readCount == -1) {
                    return;
                }
            }
        });

回答1:

Apparently in iOS 5.1 writing to stdout was disallowed. http://spouliot.wordpress.com/2012/03/13/ios-5-1-vs-stdout/

来源：https://stackoverflow.com/questions/10884913/stdout-redirection-not-working-in-ios-without-debugger