GCDAsyncSocket doesn't throw error

I'm writing simple Telnet client on Swift for Mac OS. I'm connecting to port 9052 on localhost and sending three simple commands. That's my code:

import Cocoa
import CocoaAsyncSocket

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    var socket : GCDAsyncSocket!

    func applicationDidFinishLaunching(aNotification: NSNotification) {
        requestIdentity()
    }

    func requestIdentity() -> Bool {

        socket = GCDAsyncSocket(delegate: self, delegateQueue: dispatch_get_main_queue())
        let port : UInt16 = 9052
        do {
            try socket.connectToHost("127.0.0.1", onPort: port, withTimeout: 2.0)
        } catch let e {
            print("Error \(e) accured while connecting to \(port) on 127.0.0.1")
            return false
        }
        print("connection working")

        return true
    }

    func applicationWillTerminate(aNotification: NSNotification) {

    }

    func socket(socket : GCDAsyncSocket, didReadData data : NSData, withTag : UInt16) {
        let response = String(data: data, encoding: NSUTF8StringEncoding)
        print("Got response : \(response)")
    }

    func socket(socket : GCDAsyncSocket, didConnectToHost host : String, port  p: UInt16) {
        print("Connected to host \(host) on port \(p)")
        var request = "AUTHENTICATE \"1728390\"\n"
        var data = request.dataUsingEncoding(NSUTF8StringEncoding)
        socket.writeData(data, withTimeout: -1.0, tag: 0)
        socket.readDataWithTimeout(-1.0, tag: 0)
        request = "SIGNAL NEWNYM\n"
        data = request.dataUsingEncoding(NSUTF8StringEncoding)
        socket.writeData(data, withTimeout: -1.0, tag: 0)
        socket.readDataWithTimeout(-1.0, tag: 0)
        request = "QUIT\n"
        data = request.dataUsingEncoding(NSUTF8StringEncoding)
        socket.writeData(data, withTimeout: -1.0, tag: 0)
    }


}

I intentionally close port 9052, but the socket is always "connected" - it doesn't throw any error and doesn't give any output - it just doing nothing. How to fix this?

Found the solution: when the connection times out, the

func socketDidDisconnect(sock: GCDAsyncSocket!, withError err: NSError!)

is called.