Implementing PencilKit with PDFKit

My app shows PDF files using the PDFKit and lets users make annotations on pdf files through my own code using UIKit and CoreGraphics frameworks. Since I would like to use the PencilKit framework to make annotations better, I’m in the process to implement the PencilKit framework but I’ve found some issues which I am stuck with.

What I did is to add a PKCanvasView over the DocumentView of a PDFView. In essence, it works fine, I can annotate using the tools of the PencilKit and I can navigate through the pages of the PDF.

The problem appears when I zoom-in on a PDF page. Since the PKCanvasView is not zooming itself as it’s inside the DocumentView, the ink annotations appear pixelated. The PKCanvasView is not redrawing its content with a new scale because its zoom has not changed and updating the contentScaleFactor to make the drawing sharper doesn’t work.

Another problem is, in some way related to the previous one, since the app fits each PDF page to use all the screen, this makes the zoom of the UIScrollView, which contains the DocumentView of the PDFView, vary in function of the size of the PDF page. This makes that if I open a PDF which has small pages and another with large pages, in terms of size (Width x Height), I will see the width of the lines of the inking tool with different sizes even if I have selected the smallest line width on the PKToolPicker for both files.

So I wonder if it could be possible to add a PKCanvasView and a PDFView separately to a UIViewController’s view, so they both have the same superview, with the same ContentSize and maximum/minimum zoom level and, when panning and zooming on the PKCanvasView, the PDFView does too.

Anyway, if there's a workaround I would be happy to know. ;)

from Implementing PencilKit with PDFKit