iText 7 re-labels by custom name c#

Question

I found this source code here. My question is how to rename the label by custom name without number. I think this code's row is similar, but without number is my purpose:

pdfDoc.GetPage(4).SetPageLabel(PageLabelNumberingStyle.DECIMAL_ARABIC_NUMERALS, "Custom-", 2);

using System.IO;
using iText.IO.Font.Constants;
using iText.Kernel.Font;
using iText.Kernel.Geom;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Action;
using iText.Kernel.Pdf.Annot;
using iText.Kernel.Pdf.Canvas;
using iText.Kernel.Pdf.Xobject;
using iText.Layout;
using iText.Layout.Element;

namespace iText.Samples.Sandbox.Objects
{
    public class PageLabels
    {
        public static readonly string DEST = "results/sandbox/objects/page_labels.pdf";

        public static void Main(string[] args)
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();
            new PageLabels().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(string dest)
        {
            PdfDocument pdfDoc = new PdfDocument(new PdfWriter(dest));
            Document doc = new Document(pdfDoc);

            PdfViewerPreferences viewerPreferences = new PdfViewerPreferences();
            viewerPreferences.SetPrintScaling(PdfViewerPreferences.PdfViewerPreferencesConstants.NONE);
            pdfDoc.GetCatalog().SetPageMode(PdfName.UseThumbs);
            pdfDoc.GetCatalog().SetPageLayout(PdfName.TwoPageLeft);
            pdfDoc.GetCatalog().SetViewerPreferences(viewerPreferences);

            doc.Add(new Paragraph("Hello World"));
            doc.Add(new Paragraph("Hello People"));

            doc.Add(new AreaBreak());
            PdfFont font = PdfFontFactory.CreateFont(StandardFonts.HELVETICA);
            
            // Add the text to the direct content, but not in the right order
            PdfCanvas canvas = new PdfCanvas(pdfDoc.GetPage(2));
            canvas.BeginText();
            canvas.SetFontAndSize(font, 12);
            canvas.MoveText(88.66f, 788);
            canvas.ShowText("ld");
            canvas.MoveText(-22f, 0);
            canvas.ShowText("Wor");
            canvas.MoveText(-15.33f, 0);
            canvas.ShowText("llo");
            canvas.MoveText(-15.33f, 0);
            canvas.ShowText("He");
            canvas.EndText();
            PdfFormXObject formXObject = new PdfFormXObject(new Rectangle(250, 25));
            new PdfCanvas(formXObject, pdfDoc)
                .BeginText()
                .SetFontAndSize(font, 12)
                .MoveText(0, 7)
                .ShowText("Hello People")
                .EndText();
            canvas.AddXObjectAt(formXObject, 36, 763);

            pdfDoc.SetDefaultPageSize(new PageSize(PageSize.A4).Rotate());
            doc.Add(new AreaBreak());
            doc.Add(new Paragraph("Hello World"));

            pdfDoc.SetDefaultPageSize(new PageSize(842, 595));
            doc.Add(new AreaBreak());
            doc.Add(new Paragraph("Hello World"));

            pdfDoc.SetDefaultPageSize(PageSize.A4);
            doc.Add(new AreaBreak());
            pdfDoc.GetLastPage().SetCropBox(new Rectangle(10, 70, 525, 755));
            doc.Add(new Paragraph("Hello World"));

            doc.Add(new AreaBreak());
            pdfDoc.GetLastPage().GetPdfObject().Put(PdfName.UserUnit, new PdfNumber(5));
            doc.Add(new Paragraph("Hello World"));

            doc.Add(new AreaBreak());
            pdfDoc.GetLastPage().SetArtBox(new Rectangle(36, 36, 523, 770));
            Paragraph p = new Paragraph("Hello ")
                .Add(new Link("World", PdfAction.CreateURI("http://maps.google.com")));
            doc.Add(p);
            PdfAnnotation a = new PdfTextAnnotation(
                    new Rectangle(36, 755, 30, 30))
                .SetTitle(new PdfString("Example"))
                .SetContents("This is a post-it annotation");
            pdfDoc.GetLastPage().AddAnnotation(a);

//Set page's label here:
            pdfDoc.GetPage(1).SetPageLabel(PageLabelNumberingStyle.UPPERCASE_LETTERS, null);
            pdfDoc.GetPage(3).SetPageLabel(PageLabelNumberingStyle.DECIMAL_ARABIC_NUMERALS, null);
            pdfDoc.GetPage(4).SetPageLabel(PageLabelNumberingStyle.DECIMAL_ARABIC_NUMERALS, "Custom-", 2);

            doc.Close();
        }
    }
}//

Answer 1

For the SetPageLabel method, both the first argument (numbering style) and the second (page label prefix) may be null, in order to omit them from the page labeling style.

To set a page label without numbering for page 4:

pdfDoc.GetPage(4).SetPageLabel(null, "Label without numbering", 2);