iOS Swift: a view controller as the root view controller

Question

I know how to make a view controller the root view controller of the app by this code:

window.rootViewController = (your root view controller())

but I saw also this:

 instantiateInitialViewController

and this:

instantiateViewController(withIdentifier:)

are they the same as rootViewController or they have different functionalities?

Answer 1

• instantiateInitialViewController instantiates the view controller marked as initial in a given storyboard. There can be only one initial view controller per storyboard.
• instantiateViewController(withIdentifier:) instantiates the view controller with a matching identifier from a given storyboard.

Both methods can be used to instantiate a root view controller, but also non-root view controllers you'd want to present later in the app.