Swift example for GCDAsyncSocketDelegate - ios

Question

Refer to this post I have some issues while receiving data from GCDAsyncSocket and can't find a working Swift example.
import UIKit
import CocoaAsyncSocket
class DiscoveryViewControllerTest: UIViewController, GCDAsyncSocketDelegate{
let host = "192.168.55.1"
let port:UInt16 = 4000
let cmdDeviceInformation = "?0600\r";
let cmdDeviceIStandByeExit = "?060B\r";
let cmdDeviceIStandByeEnter = "?060A\r";
var mSocket: GCDAsyncSocket!
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
print("Started wifi scanning!\n")
mSocket = GCDAsyncSocket(delegate: self, delegateQueue: DispatchQueue.main)
do {
try mSocket.connect(toHost: host, onPort: port)
} catch let error {
print(error)
}
print("Connecting to instrument...!\n")
}
public func socket(_ socket: GCDAsyncSocket, didConnectToHost host: String, port p:UInt16){
print("didConnectToHost!\n");
let data = cmdDeviceIStandByeEnter.data(using: .utf8)
print("TX: ", terminator: " ")
print(data! as NSData)
mSocket.write(data!, withTimeout:10, tag: 0)
mSocket.readData(withTimeout: -1, tag: 0) //This line was missing!
}
public func socket(_ sock: GCDAsyncSocket, didWriteDataWithTag tag: Int) {
print("didWriteData");
}
public func socket(_ sock: GCDAsyncSocket, didReceive trust: SecTrust, completionHandler: #escaping (Bool) -> Void) {
print("didReceiveData")
let rxData:Data = Data()
mSocket.readData(to: rxData, withTimeout: 5, buffer: nil, bufferOffset: 0, tag: 0)
print("RX: ", terminator: " ")
print(rxData as NSData)
}
public func socket(_ sock: GCDAsyncSocket, didRead: Data, withTag tag:CLong){
print("didRead!");
}
public func socketDidDisconnect(_ sock: GCDAsyncSocket, withError err: Error?) {
print("didDisconnect!")
}
}
The connecting and writing method is running but the "didReceive" Method is never called.
Console output:
Started wifi scanning!
Connecting to instrument...!
didConnectToHost!
TX: <3f303630 410d> didWriteData
EDIT
I solved my problem and changed the question code to a ready to use example.

Answer 1

I have found my fault. The clue is to enable reading just behind the mSocket.write() function call in socket didConnectToHost(). The complete function looks like this:
public func socket(_ socket: GCDAsyncSocket, didConnectToHost host: String, port p:UInt16){
print("didConnectToHost!\n");
let data = cmdDeviceInformation.data(using: .utf8)
print("TX: ", terminator: " ")
print(data! as NSData)
mSocket.write(data!, withTimeout:10, tag: 0)
mSocket.readData(withTimeout: -1, tag: 0) // Add this line
}
BTW: I edited my question to create a ready to use example for everyone.