Constraints for a child view controller within a subview

When a UIViewController is added within one of it's parent's subviews, there can be an issue where it doesn't expand to fill it. This can often happen when we only tested on a specific device size.

The fix involves preventing the auto-resizing mask from being turned into constraints and ensuring the child view controller's anchor constraints are all attached to the edge's of its container view.

addChild(child)
containerView.addSubview(child.view)
child.view.translatesAutoresizingMaskIntoConstraints = false
child.view.attachAnchors(to: containerView)
child.didMove(toParent: self)

I hope the article was useful. If you have any feedback or questions please feel free to reach out.

Thanks for reading!