PencilKit: Building a complete drawing app with a few lines of code

image from

In WWDC2019, Apple gifted us with a brand new Apple Pencil framework: the PencilKit. Before that, it was very hard and complex to build a Pencil app only by detecting touching gestures and making Math calculations, but with this new library, it costs only a few lines of code to present a drawing canvas with a simple tool picker.