SwiftyZeroMQ Publisher does not recognise subscriber after first message is published

I did some more testing and found out a few things and a workaround.

1. The code works as intended when running on an iPhone simulator (simulator is x86_64 architecture, iPhone8 is armv7)
2. I don't think it is related, but I did find it interesting. Certain multicast and broadcast protocols require an approval from Apple. You can run without the approval on simulators, but not in devices. Apple networking multicast entitlement. Since it partially works I did rule this out.
3. The workaround is to bind the socket again prior to each publish. This throws the error "Address already in use", butt seem to not do much harm.
4. Without unreasonable delays in between publish messages, the pub-sub fails after 500-1000 messages if the publish socket is not binded again when running from the iPhone.

I made a minimal working example app that you can play around with if you want to, or need to dig deeper. It has buttons for "init", "bind", "publish" and "bind and publish". You can send a batch of messages and check timings etc. I run the app towards a python3 script. I included SwiftyZeroMQ5 via cocoapods.

Podfile:

platform :ios, '13.0'
target 'ZMQtest' do
  use_frameworks!
  pod 'SwiftyZeroMQ5'
end

SwiftCode (set up the buttons your self..)

import UIKit
import SwiftyZeroMQ5
class ViewController: UIViewController {
    let context = try! SwiftyZeroMQ.Context()
    var publisher: SwiftyZeroMQ.Socket?
    let publishEndPoint = "tcp://*:5560"
    var cnt = 0
    let quota = 1200
    @IBAction func publishButtonPressed(_ sender: Any) {
        while cnt < quota {
            publish()
            //usleep(10000)
        }
        cnt = 1
    }
    @IBAction func bindAndPublishButtonPressed(_ sender: Any) {
        while cnt < quota {
            bindPublisher()
            publish()
        }
        cnt = 1
    }
    @IBAction func initPubButtonPressed(_ sender: Any) {
        initPublisher()
    }
    @IBAction func bindPublisherButtonPressed(_ sender: Any) {
        bindPublisher()
    }
    @IBOutlet weak var statusLabel: UILabel!

    // **************
    // Init publisher
    func initPublisher(){
        do {
            self.publisher = try context.socket(.publish)
            print("Publisher socket created")
        }
        catch {
            print("initPublisher error: ", error)
        }
     }

    // **************
    // Bind publisher
    func bindPublisher(){
        do {
            try self.publisher?.bind(publishEndPoint)
            print("Publisher socket binded to :", publishEndPoint)
        }
        catch {
            print("bindPublisher error: ", error)
        }
    }

    // *****************
    // Publish a message
    func publish(){
        // Publish dummy string
        do{
            cnt += 1
            let str = "topic {\"key\": \"" + String(cnt) + "\"}"
            try self.publisher?.send(string: str)
            statusLabel.text = str
            print("Publish message no: ", String(cnt))
        }
        catch{
            print("publisher error: ", error)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

And the python3 code:

#!/usr/bin/env python3
'''Minimal running example of a ZMQ SUB socket.'''
import json
import zmq

def demogrify(msg: str):
  '''inverse of mogrify()'''
  try:
    (topic, message) = msg.split(maxsplit=1)
  except ValueError:
    (topic, message) = (msg, '{}')

  return topic, json.loads(message)

def close_socket_gracefully(socket):
  '''graceful termination'''
  socket.setsockopt(zmq.LINGER, 0) # to avoid hanging infinitely
  socket.close()

if __name__ == "__main__":
  context = zmq.Context()

  socket = context.socket(zmq.SUB)  #pylint: disable=no-member
  socket.connect("tcp://192.168.1.2:5560")
  socket.setsockopt_string(zmq.SUBSCRIBE, '')  #pylint: disable=no-member
  socket.RCVTIMEO = 1000  # in milliseconds

  while socket:
    try:
      msg = str(socket.recv(), 'utf-8')
      (topic, msg) = demogrify(msg)
      print((topic, msg))
    except zmq.error.Again as error:
      print(str(error))
    except KeyboardInterrupt:
      close_socket_gracefully(socket)
      socket = None

Should I mark this issue as solved or not?