Here's something useful to know - [UIView’s](https://developer.apple.com/documentation/uikit/uiview) are backed by [CALayer’s](https://developer.apple.com/documentation/quartzcore/calayer). Layers offer a lower-level interface to the visual content. When we need more flexibility or performance, we can go to layer level.
Animation has been an important part of the Mac OS X user interface since the very beginning. You’ve probably seen the Genie effect, which occurs when you minimize an application, so many times that you hardly notice it anymore. Apple integrates animation into its operating systems and applications, and it is becoming so commonplace that users are starting to expect it. Core Animation is a group of features that makes it easy to build animated user interfaces for the Apple ecosystem devices like iPhone, iPad, Apple TV, and Mac.
Animating a UIBezierPath drawing is a pretty trivial task. But how to animate shape morphing, i.e. make one shape change into another? (For instance, morphing a triangle into a square.) To accomplish this, we need to use CAShapeLayer and animate its properties using Core Animation capabilities.