Swift: Receive UDP with GCDAsyncUdpSocket

Question

BACKGROUND:

I want to be able to send and receive UDP packets between my iOS app and a server. The server echoes back every incoming message to the client the app. The server is tested and confirmed working. I have a StartViewController which starting up two classes that implements GCDAsyncUdpSocketDelegate, one for sending and one for receiving. The "sending socket" is working, the server receives the messages.

PROBLEM:

The app never get the incoming message back after it been sent. Something with the listening socket setup is probably wrong since didReceiveData never get called.

Have I done this completely wrong?

Start:

class StartViewController: UIViewController {

   var inSocket : InSocket!
   var outSocket : OutSocket!

   override func viewDidLoad() {
       super.viewDidLoad()
       inSocket = InSocket()
       outSocket = OutSocket()
   }

   @IBAction func goButton(sender: UIButton) {
       outSocket.send("This is a message!")
   }
}

Receive:

class InSocket: NSObject, GCDAsyncUdpSocketDelegate {

   let IP = "255.255.255.255"
   let PORT:UInt16 = 5556
   var socket:GCDAsyncUdpSocket!

   override init(){
       super.init()
       setupConnection()
   }

   func setupConnection(){
       var error : NSError?
       socket = GCDAsyncUdpSocket(delegate: self, delegateQueue: dispatch_get_main_queue())
       socket.bindToPort(PORT, error: &error)
       socket.enableBroadcast(true, error: &error)
       socket.joinMulticastGroup(IP, error: &error)
       socket.beginReceiving(&error)
   }

   func udpSocket(sock: GCDAsyncUdpSocket!, didReceiveData data: NSData!, fromAddress address: NSData!,      withFilterContext filterContext: AnyObject!) {
       println("incoming message: \(data)");
   }
}

Send:

class OutSocket: NSObject, GCDAsyncUdpSocketDelegate {

   let IP = "90.112.76.180"
   let PORT:UInt16 = 5556
   var socket:GCDAsyncUdpSocket!

   override init(){
       super.init()
       setupConnection()
   }

   func setupConnection(){
       var error : NSError?
       socket = GCDAsyncUdpSocket(delegate: self, delegateQueue: dispatch_get_main_queue())
       socket.connectToHost(IP, onPort: PORT, error: &error)
   }

   func send(message:String){
       let data = message.dataUsingEncoding(NSUTF8StringEncoding)
       socket.sendData(data, withTimeout: 2, tag: 0)
   }

   func udpSocket(sock: GCDAsyncUdpSocket!, didConnectToAddress address: NSData!) {
       println("didConnectToAddress");
   }

   func udpSocket(sock: GCDAsyncUdpSocket!, didNotConnect error: NSError!) {
       println("didNotConnect \(error)")
   }

   func udpSocket(sock: GCDAsyncUdpSocket!, didSendDataWithTag tag: Int) {
       println("didSendDataWithTag")
   } 

   func udpSocket(sock: GCDAsyncUdpSocket!, didNotSendDataWithTag tag: Int, dueToError error: NSError!) {
        println("didNotSendDataWithTag")
   }
}

Edit: Added forgotten code line.

Answer 1

I finally got it to work with this socket setup:

func setupConnection(){
    var error : NSError?
    socket = GCDAsyncUdpSocket(delegate: self, delegateQueue: dispatch_get_main_queue())
    socket.bindToPort(PORT, error: &error)
    socket.connectToHost(SERVER_IP, onPort: PORT, error: &error)
    socket.beginReceiving(&error)
    send("ping")
}

func send(message:String){
   let data = message.dataUsingEncoding(NSUTF8StringEncoding)
   socket.sendData(data, withTimeout: 2, tag: 0)
}