How to switch between different ViewControllers or NavigationController in Swift?

Question

I just got into Swift programming lately and I have an easy question I can't answer.

I understood that we start putting a ViewController to show something, then if I want to display another view I can use a segue linked to another view. But I don't like the fact that the view called by the segue doesn't take the full screen. It just looks like a pop-up screen.

So, how could I switch from a ViewController to another ViewController or NavigationController or whatever that keep the fullscreen view. How could I change my view without passing through a segue and get the following view like a pop-up ?

Hope my wonder is clear enough to be answered :D

Thanks a lot to the community !!!