El cliente envió un mensaje cada vez que presiono el botón Enviar, pero el servidor recibe el mensaje solo la primera vez. ¿Cuál es el problema en el servidor?

Servidor:

- (void)viewDidLoad
{
    [super viewDidLoad];

    asyncSocket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

    NSError *err = nil;
    if (![asyncSocket acceptOnPort:10000 error:&err]){

        NSLog(@"Error in acceptOnPort:error: -> %@", err);

    }
}

- (void)socket:(GCDAsyncSocket *)sock didAcceptNewSocket:(GCDAsyncSocket *)newSocket
{
    NSLog(@"Accepted new socket from %@:%hu", [newSocket connectedHost], [newSocket connectedPort]);

    self.asyncSocket = newSocket;
    NSString *welcomMessage = @"Hello from the server\r\n";
    [self.asyncSocket writeData:[welcomMessage dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:1];

    [self.asyncSocket readDataWithTimeout:-1 tag:0];

}

-(void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag{
    NSString *msg = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

    NSLog(@"MSG: %@",msg);

}

Cliente:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    socket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
    [socket setDelegate:self];

}

-(IBAction)connectToServer {
    NSError *err = nil;
    if (![socket connectToHost:self.txtIp.text onPort:10000 error:&err]) // Asynchronous!
    {
        // If there was an error, it's likely something like "already connected" or "no delegate set"
        NSLog(@"I goofed: %@", err);
        return;
    }
}

- (void)socket:(GCDAsyncSocket *)sender didConnectToHost:(NSString *)host port:(UInt16)port
{
    NSLog(@"Cool, I'm connected! That was easy.");

     [socket readDataWithTimeout:-1 tag:0];
}

- (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag
{
    if (tag == 1)
        NSLog(@"First request sent");
    else if (tag == 2)
        NSLog(@"Second request sent");
}

- (void)socket:(GCDAsyncSocket *)sender didReadData:(NSData *)data withTag:(long)tag
{
    NSLog(@"Received Data: %@",data);
}


-(void)sendMessage {

    NSData *msg = [self.txtMsg.text dataUsingEncoding:NSUTF8StringEncoding];

    NSLog(@"Data Send: %@",msg);

   [socket writeData:msg withTimeout:-1 tag:1];

}