How to create .drawing file for PencilKit?

Question

If you look at Apple's PencilKit Sample, you'll noticed apple used a dataset file called Notes.dataset to save Pencilkit draws. Inside the Notes.dataset, it contains a general json file for Asset Catalogue.

But more interesting, there is a file called color.drawing, which saves the actual data produced by Pencilkit. My question is, how do you create this file as a developer? For example, I want to create a tutorial using Pencilkit and save it as a ".drawing" file, to load up on first launch.

Answer 1

PKDrawing is a model layer of PencilKey (and it is opaque), and here is API to store/restore that model:

   func dataRepresentation() -> Data // << to store data in file
   init(data: Data) throws // << to restore from data read from file