This sample shows a issue of Apple PDFKit when making changes to PDF files.

This example has a Highlight text feature, select a text, tap "Highlight" on Touch Bar, changes will automatically save.

PDFDocument.write(toFile:) (document) breaks vertical writting PDF documents.

Find a vertical writting PDF document that text can select vertically.

Download the example doucment.

Check if document text can be select vertically.

Open this document in PDFReader-Mac.

Select a text, tap "Hightlight" on Touch Bar.

Close and open file again.

You can see vertical text selection is broken.