I agree. Affinity Designer solves the problem. It would be nice if Illustrator could do this as well.

Any further developpement about this request ?

As an architect working with many layers this feature is crutial to my workflow.

Thanks for fixing this :)

Regards,
-CC

Completely agree. Many times we need to use PDFs from other software which have Acrobat layers but importing in Illustrator flattens all the layers. Sometimes this causes lots of pain when we need to reorganize the contents on different layers.

@Rob: I agree entirely with your comment and the original post's request. It'd sure be nice if Illustrator could see the OCG's and re-interpret them as its own layers somehow. I'm not sure how they'd handle objects that are assigned to more than one OCG though. How does Affinity Designer handle that? I don't have it here at my workplace to test on, unfortunately.

Hey thanks for the info @Lance.

Let's rephrase this ask then "Illustrator should add support for 'Optional Content Groups' if that's what it takes. Or basically to do whatever it is Affinity are doing ... because when you open a PDF in Affinity Designer, that 'little' £50 application is once again showing Adobe (who created the PDF standard) how things should be done. There isn't a clipping mask in sight and although not perfect (and inverted from the Acrobat layer stack) I can glean more info from the layer structure in Designer than I can from Illustrator - see layer examples from the attached screenshots.

Sure in an ideal world we wouldn't be using PDFs but the world can be far from ideal and we all need workarounds to make things happen. This feature request is trying to make a workaround work better.

Very interesting technical explanation Lance, thank you. Appreciate the acknowledgement that sometimes what I call "can-opening" a PDF in Illustrator is the only tool we have. If it can be described, seems like it could also be solved. :D

For those of you commenting below:

Z-order / stacking order layers CANNOT be saved from authoring software into a PDF. All you can do is save PDF "layers", which are not z-order/stacking order layers but are instead known as "optional content groups", OCG's.

A single path object can be in multiple OCG's, while another may only be in one (and that one may be one that the first object was also located in as well) The OCG's visibility can be switched on and off with software capable of seeing them, such as the paid version of Acrobat, and various professional preflighting programs.

Illustrator does not see OCG's. In reality, illustrator should never be used to open and edit a PDF, though I do understand sometimes there is no other choice.

Ditto on Rob and Kate's comments. My team receives PDFs of ArtiosCAD file for packaging. Being able to keep the layers when opening in Illustrator is very helpful for creating the packaging graphics. It's very time consuming to separate out all the little CAD lines into individual layers again. Since ArtiosCAD files only export as PDFs for opening in Illustrator, I'm hoping Illustrator can provide a solution.

I agree with Rob's comment. We receive PDF versions of CAD files from architects. the PDF shows the layers, but the Illustrator removes all layers. Would love to see the layers transfer into Illustrator.

Correct, not just about InDesign. I also experience PDFs created by CAD programs that Rob refers to below. Spending hours unpicking the damage is definitely one way to put it! For me, this workflow is related to files shared by many users at a few different locations and companies that collaborate but don't share the same file source site. Here's an example of the layers in the original file and then after it is saved as a PDF and then opened in Illustrator from the PDF.

This isn't just related to InDesign, I likewise receive PDFs generated by CAD programs which contains layers when view in Acrobat but when you open these in Illustrator the structure is obliterated.

This needs to be addressed as you can waste hours trying to unpick the damage done.

I totally agree. This is a major problem to solve.