How to simulate multiple iOS clients connecting to a server?

I am creating a service and an iOS client app that will connect to the service. I am trying to make the client app modular, loosely coupled in its structure.

At some moment I will want to see how multiple clients connect to a service at one moment and how everything is performing.

What are the tools/approach to handle this task? Should I create a CLI utility app for Mac OS that inherits from iOS client app classes?

Should I create the iOS app the way that it has interfaces to its code to be consumed as something like API so that to interact with it from the CLI app?

Ideally, I would like to just run the part of the code that is in charge of business-logic, not UI stuff, so just seeing app logs in console is fine, not having to see 10 similar windows of the same working iOS app.

What are the solutions big boys use?