Is it possible to set constraints for root view in XIB?

Question

Recently i was following a tutorial to create frameworks in Swift, Where they create reusable visual effect view just like we see in Xcode build success pop up. I was doing the UI step by step where they created a new xib file and dragged and dropped UIVisualEffectView into it.

In the above image we can see that the UIVisualEffectView doesn't contain any constraints. It only has auto resizing masks in size inspector(as expected).

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But the following image from the tutorial suddenly contains all necessary constraints for it's root view.

I'm already aware that we CANNOT, by default set any constraints for the root view. But in the tutorial the author seems to have added constraints for the same. I'm just curious to know if it is possible to do that or am i missing any fundamental idea ?

EDIT:

Constraints for root view.

Answer 1

OK, found one way to do this...

Haven't done any testing, so I'm not sure if the constraints are really set correctly or will be used by auto-layout at run-time, but this will put them there.

Create a new "View" XIB - this is how it looks to start:

Add a Visual Effect view to this view, and give it width and height constraints of 230 / 230:

Now, drag that Visual Effects view *out of the plain view, onto an empty space:

You will see it maintains its constraints. Then delete the original view, and add the other elements:

Answer 2

As you can actually see on your screenshot the width/height constraints belong to the View (first subview of Visual Effect View).

Look at the green line: