How can I detect rectangles and boxes in PDF using C# iTextsharp

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C#

PDF

itextsharp

I have a sample of PDF that looks like this
https://i.stack.imgur.com/VDp9I.png[^]

However, unfortunately, the rectarray comes back as null. I tried BOX instead of RECT, but rectarray also comes back as null

PdfReader reader = new PdfReader(inFileName);

        for (int i = 1; i <= reader.NumberOfPages; ++i)
        {
            strPageNumber = i.ToString();
            if (intCommentCount >= 5)
            {
                break;
            }

            PdfDictionary pagedic = reader.GetPageN(i);

            var thing = reader.GetPageContent(i);
            string converted = Encoding.UTF8.GetString(thing, 0, thing.Length);
            PdfArray rectarray = (PdfArray)PdfReader.GetPdfObject(pagedic.Get(PdfName.RECT));

            if (rectarray == null || rectarray.Size == 0)
            {
                continue;
            }
         }

What is the way to collect BOX/RECTANGLE objects from the PDF using C# iTextSharp

Thank you in advance

What I have tried:

I tried BOX instead of RECT, but rectarray also comes back as null