How to make self sizing for child controller view?

Question

Swift

I will add a child controller to the parent controller, I will add a child view.

addChild(childController)
view.addSubview(childController.view)
childController.didMove(toParent: self)

The size of a child controller depends on the content in it. The parent is not aware of the content in the child.
How to make a layout so that the height of the child controller changes for a certain content width?

It works with auto layout out of the box, I did not find an implementation on frames.

PS Redefine sizeThatFit will not work, because it is a view controller.

Answer 1

To do this on a frame, you need:

1. at the end of the recalculation of dimensions, set in the child
   preferredContentSize
   
2. When setting the size, the method on the parent will be calledpreferredContentSizeDidChange
   
3. In the method call, recalculate the layout in the parent, knowing the desired height of the child. There will be no call cycle, notification is not called if the size matches.