How to get and set value for /BSIColumnData of an annotation PDF itext c#

Question

How to get and set value for /BSIColumnData of an annotation (markup) in PDF using itext c# as attached file? I'm using Itext7 code below, but it is error at BSIColumnData:

public void BSIcontents ()
    {
        string pdfPath = @"C:\test PDF.pdf";
        iText.Kernel.Pdf.PdfReader pdfReader = new iText.Kernel.Pdf.PdfReader(pdfPath);
        iText.Kernel.Pdf.PdfDocument pdfDoc = new iText.Kernel.Pdf.PdfDocument(pdfReader);
        int numberOfPages = pdfDoc.GetNumberOfPages();

        int z = 0;
            for (int i = 1; i <= numberOfPages; i++)
            {
                iText.Kernel.Pdf.PdfDictionary page = pdfDoc.GetPage(i).GetPdfObject();
                iText.Kernel.Pdf.PdfArray annotArray = page.GetAsArray(iText.Kernel.Pdf.PdfName.Annots);
                if (annotArray == null)
                {
                    z++;
                    continue;
                }
                int size = annotArray.Size();
                for (int x = 0; x < size; x++)
                {
                    iText.Kernel.Pdf.PdfDictionary curAnnot = annotArray.GetAsDictionary(x);
                    if (curAnnot != null)
                    {
                        if (curAnnot.GetAsString(iText.Kernel.Pdf.PdfName.BSIColumnData) != null)
                        {
                            MessageBox.Show("BSIColumnData: " + curAnnot.GetAsString(iText.Kernel.Pdf.PdfName.BSIColumnData).ToString());
                        }
                    }
                }
            }
        pdfReader.Close();
    }

In Bluebeam Revu, you can see as below:

In Itext-rups 5.5.9, you can see as below:

Answer 1

I see two errors:

• You try to use the BSIColumnData name like this:

  iText.Kernel.Pdf.PdfName.BSIColumnData
  

  This assumes that there is already a static PdfName member for your custom name. But of course there isn't, there only are predefined members for standard names used in itext itself. If you want to work with other names, you have to create a PdfName instance yourself and use that instance, e.g. like this

  var BSIColumnData = new iText.Kernel.Pdf.PdfName("BSIColumnData");
  

• You try to retrieve the value of that name as string

  curAnnot.GetAsString(iText.Kernel.Pdf.PdfName.BSIColumnData)
  

  but it is clear from your RUPS screenshot that the value of that name is an array of strings. Thus, even after correcting as described in the first item GetAsString(BSIColumnData) will return null. Instead do

  var BSIColumnData = new iText.Kernel.Pdf.PdfName("BSIColumnData");
  var array = curAnnot.GetAsArray(BSIColumnData);
  

  After checking if (array != null) you now can access the strings at their respective indices using array.GetAsString(index).