CocoaMQTT | MQTT 5.0 client library for iOS and macOS written in Swift | iOS library

I have singleton class

I am making one iOS app communicating with Mqtt broker, mainly to publish message. But when I try to connect with broker using CocoaMQTT library it's always giving me error in connection.

I am trying with CocoaMQTT latest version and also 1.1.3 version. But both are failing in connection and giving me error

(Error Domain=kCFStreamErrorDomainNetDB Code=8 "nodename nor servname provided, or not known" UserInfo={NSLocalizedDescription=nodename nor servname provided, or not known})

I have produced an app that connects to a raspberry pi's own wifi network and sends a message to give some data to it. I was using the cocoamqtt Library found here but I couldn't find a way to know when the client connects successfully or not so I move to the Moscapsule Library found here. I could easily connect to my pi with the cocoamqtt library, but whenever I try to connect to the pi with the Moscapsule library it just says 'Received DISCONNECT from iDevice' as soon as it makes a connection.

Here's my code:

I'm trying to set up a connection using CocoaMQTT. The following example is provided on the GitHub page:

https://github.com/emqx/CocoaMQTT/blob/master/Example/Example/ViewController.swift

They are using a view controller 'self' as the delegate (see lines 53/63/74). However, when I try to use the view controller as the delegate, I get the error:

I completed a few months ago a project with CocoaMQTT. Now I want to do a new project and I created the files like the one before. Now I get this error-codes. When I click the button to update the Code, I get new error-codes. Got someone the same problem or know a solution?

i have a problem with my mqttconfiguration. Connection works fine. Every time I send a message, switch to another ViewController, come back and push again the sending button, no message received at my raspberry. So the problem is, when I switch over multiple ViewController I can't send messages anymore. I don't find my mistake in my code:

Swiftfile for MQTT-Config:

I have a Raspberry Pi with a temperature sensor, that has a python script which constantly publishes the temperature using MQTT, and I have set the interval for every 1sec. In the iOS app I am making I have an MQTTManager class which has an mqttClient that subscribes to its topic and receives the string with the temperature. In the main view of my app I want to display the temperature and have it constantly updated, with the same (or close to the same) speed as the python script is sending it. The idea I have so far is to have the text of a UILabel be updated with the message string from the mqtt client message. I am not sure how update the label text correctly, with every sent publish event. I know I need to set up some kind of event handler for this message but I am not sure how to go about it. Any help will be appreciated.

UPDATE: With the code that I have so far. This is my mqttManager:

I am going to update my customised sample based on Build a home assistant mobile application with Watson and IoT Platform services

I did:

1. carthage update --platform iOS
2. did the pod install
3. Using the autofix for the API Changes of the Watson Conversation Parameter inside xCode
4. Asking a question about: How to handle a concrete situation with a parameter, here on Stack Overflow

And now I got a linker error and I do not now is the error related to the update of the API or is it related to a newer xCode version, or the RestKit?

In this code I get the message:

d: framework not found RestKit clang: error: linker command failed with exit code 1 (use -v to see invocation)'

I have class named MQTTController with shared instance and a private init method