ios - Why can't we put subviews of a UIView in front of its CALayer?

Question

As the title of this post, I found the answer regarding "Can we put subviews of a UIView in front of its CALayer" in this post, but I cannot find the answer to why this is so. In my opinion, having the view as the subview of the layer's view only suggests "stronger" order between the subview and the layer. Can somebody explain this to me?

Answer 1

Each view is backed by a CALayer and the layer tree is a superset of the view tree. Therefore every subview you add to a view has its corresponding layer added to its superview's layer. Since its a child of the parent layer and layers are rendered from the top of thee tree down, you cannot change the render order.