moving from view controller to another view controller without using segue

Hello there

I have two view controllers vc1 and vc2.

I can go from vc1 to vc2 using segue (modal)
And I can come back from vc2 to vc1 by just dismissing the vc2. (so that it doesn't need any segue to go back from vc2 to vc1).

I would like to know how to go from vc1 to vc2 without using any segue. This vc1 is the main window which opens when app loads. Once it loads, I want to click a button which should take me to vc2.

I know its very simple but after trying so much, I am still nowhere.

If you can include a simple code, that would be greatly appreciated.

 

correct me if I am wrong, but push method works with UINavigation object. and I am working with view controller.

I don't want to fuse UINavigation. There should be some way to do this using view controller.

Any help would be great.