how to dynamically generate pdf file from html in C# using ItextSharp ?

Hi,
I am considering that your html contains inline styling which is most suitable for such dynamic pdf generation then you can easily use the following method for the purpose of converting your HTML into PDF, the method will be returning MemoryStream which can be easily downloaded as file.

public MemoryStream GeneratePdf(string html)
        {
            var pdfDoc = new Document(PageSize.A3);
            var memoryStream = new MemoryStream();
            PdfWriter pdfWriter = PdfWriter.GetInstance(pdfDoc, memoryStream);

            pdfWriter.RgbTransparencyBlending = true;
            pdfDoc.Open();

            var cssResolver = new StyleAttrCSSResolver();
            XMLWorkerFontProvider fontProvider =
                new XMLWorkerFontProvider(XMLWorkerFontProvider.DONTLOOKFORFONTS);
            //Following line will be required in case of lanuguages other than english i.e I have added following for arabic font.
            //fontProvider.Register(HttpContext.Server.MapPath("~/Tahoma Regular font.ttf"));
            CssAppliers cssAppliers = new CssAppliersImpl(fontProvider);
            HtmlPipelineContext htmlContext = new HtmlPipelineContext(cssAppliers);
            htmlContext.SetTagFactory(Tags.GetHtmlTagProcessorFactory());
            // Pipelines
            PdfWriterPipeline pdf = new PdfWriterPipeline(pdfDoc, pdfWriter);
            HtmlPipeline html1 = new HtmlPipeline(htmlContext, pdf);
            CssResolverPipeline css = new CssResolverPipeline(cssResolver, html1);
            // XML Worker
            XMLWorker worker = new XMLWorker(css, true);
            XMLParser p = new XMLParser(worker);
            p.Parse(new StringReader(html));
            pdfWriter.CloseStream = false;
            pdfDoc.Close();
            memoryStream.Position = 0;
            return memoryStream;
        }

You can simply call the above method by using the following code for example:

MemoryStream memoryStream = GeneratePdf("<div style='font-size:30px;color:#ff0000;'>Document Title</div><br/><p>document description</p>");