Replace image(s) in PDF in swift. How to get image position in page?

Question

I need to replace images in a PDFDocument or CGPDFDocument.

I found a way to extract images using the old Core Graphics API (i.e. not PDFKit). Here.

Now I would like to make a copy of a PDF but by replacing the existing images. How can I get the width/height & coordinates of the existing images in the source PDF?

PDF are sooo complicated.

Thanks!