We have had a number of reports that the inking that is produced by the pdftron sdk is not being shown on the native IOS reader regardless of whether it is a custom appearance or not. We have confirmed this with your latest test app.
Please find attached a file in which the inking does not show.
Please can you advise if this is a known issue and why this could be happening ?
The reason annotations aren’t showing with iOS’s native renderer is because it doesn’t support annotations, with or without custom appearances. To confirm this you can annotate a PDF using Apple’s own desktop program Preview and they will not be displayed in the iOS apps iBooks, Mail, Safari, or any third party app that uses Apple’s PDF renderering. (Same story if the annotations are created with PDFNet, Acrobat, etc.)
The only way that you can display “annotations” with iOS’ built-in renderer is to flatten them so that they are no longer annotations but part of the PDF content stream. This way they will show up when rendered with Apple’s renderer, but no other app will be able to manipulate them, read the comments, etc., because they are no longer annotations. You could consider giving users the option to create a flattened copy of the PDF when they want to email it or otherwise share it.