Where to set the instance of Matomo within an iOS app

Hi there,
I would like to publish a tutorial video explaining how to deploy Matomo on an iOS app, though I have no much knowledge about iOS.
I read the following documentation about iOS sdk GitHub - matomo-org/matomo-sdk-ios: Matomo iOS, tvOS and macOS SDK: a Matomo tracker written in Swift and the part I am struggling with is the following:

let matomoTracker = MatomoTracker(siteId: "23", baseURL: URL(string: "https://demo2.matomo.org/piwik.php")!)

I have no idea where I have to insert it, I understand that the pageview needs to be set on the action that’s ok, but really no idea regarding the instance definition.
Can somebody give me a hint here?

Thank you