Difference between UIWindowScene and View Controller Scene.

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Created Nov ’20

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When an app launches, UIApplicationMain creates the UIWindowScene which is used to instantiate the window. A view controller is then instantiated and assigned to the rootViewController property of the window.

In other words:

UIWindowScene -> window -> rootViewController

As far as I understand, there is usually one scene to which view controllers can be added (although you can create more than one scene).

But, when I see a storyboard, I see View Controller Scene per view controller. Are these scenes different from the window scene? If so, are these properties of UIWindowScene or the window?

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Answer 1

OOPer OP

Nov ’20

Are these scenes different from the window scene?

YES.
Seems Apple's engineer likes the word scene, but the scene in UIWindowScene and the scene in View Controller Scene are different things.

View Controller Scene just representing the UI structure, other engineers (in other frameworks) would call it with some other term, for example page.

If so, are these properties of UIWindowScene or the window?

It is hard to say yes or no, as properties may mean various things.
UIWindowScene or window is a representative of some specific area of the device (imagine user is using iPad with Split View), and at some instant, the window is showing some specific view controller which is tightly coupled with View Controller Scene.

Code Block UIWindowScene -> window -> rootViewController
                              ↑↓
                           View Controller Scene

(Hoping your browser show rootViewController and View Controller Scene vertically aligned.)

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