GCDAsyncSocket readData not called - ios

Question

I'm trying to send a message to a server and receive a response using my iPhone. I can connect to the server using:
telnet 123.123.123.1 6000
Trying 123.123.123.1...
Connected to 123.123.123.1.
Escape character is '^]'.
?VERSION
OK
VERSION=PROTOCOL: 1.1.0
?VERSION is my question
OK states it received and understood the question
VERSION= is the response from the server
so I'm trying to do the same thing but with xcode
So I have this in my viewDidLoad
dispatch_queue_t mainQueue = dispatch_get_main_queue();
asyncSocket = [[GCDAsyncSocket alloc]initWithDelegate:self delegateQueue:mainQueue];
asyncSocket.delegate = self;
NSString *host = #"123.123.123.1";
uint16_t port = 6000;
NSLog(#"Connecting to \"%#\" on port %hu...", host, port);
NSError *error = nil;
if (![asyncSocket connectToHost:host onPort:port withTimeout:5.0 error:&error])
{
NSLog(#"Error connecting: %#", error);
}
else
{
NSLog(#"Connecting...");
}
And I have the following code showing it connected
-(void)socket:(GCDAsyncSocket *)sock didConnectToHost:(NSString *)host port:
(UInt16)port
{
NSLog(#"socket:%p didConnectToHost:%# port:%hu", sock, host, port);
// We're just going to send a test string to the server.
NSString *myStr = #"?VERSION";
NSData *myData2 = [myStr dataUsingEncoding:NSUTF8StringEncoding];
[asyncSocket writeData:myData2 withTimeout:-1 tag:0];
}
And the following to show it wrote
-(void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag{
NSLog(#"WRITING");
[asyncSocket readDataToData:[GCDAsyncSocket LFData] withTimeout:-1 tag:0];
}
Sadly this never gets called
- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
NSString *tempString = [[NSString alloc]initWithData:data
encoding: NSUTF8StringEncoding];
}
I'm lost and really need some assistance

Answer 1

It is because you say write AND read at the same time. First call [asyncSocket writeData:myData2 withTimeout:-1 tag:0]; and in didWriteDataWithTag call [asyncSocket readDataToData:[GCDAsyncSocket LFData] withTimeout:-1 tag:0];. You are on one thread - dispatch_get_main_queue() - it can't do two things at one time.