Chapter 8 Layer Animations viewWillAppear

We created the following animation: let flyRightBasicAnimation = CABasicAnimation(keyPath: “position.x”)
but we added this animation in viewWillAppear…and also triggered the animation in viewWillAppear.

But for views, setup was done in view will appear but animations were triggered in viewDidAppear.

Wanted to confirm the above behaviour of layers: that if you add in viewWillAppear, the object gets added to the render tree. But is there any rendering involved between the phase viewWillAppear and viewDidAppear cycles: if yes: then layers and views will show different behaviour(in terms of timing) for the above. Any documentation which I can refer to understand the rendering cycles?