C# iTextSharp Merge multiple pdf via byte array

Question

I am new to using iTextSharp and working with Pdf files in general, but I think I'm on the right track.

I iterate through a list of pdf files, convert them to bytes, and push all of the resulting bytes into a byte array. From there I pass the byte array to concatAndAddContent() to merge all of the pdf's into a single large pdf. Currently I'm just getting the last pdf in the list (they seem to be overwriting)

public static byte[] concatAndAddContent(List<byte[]> pdfByteContent)
    {
        byte[] allBytes;

        using (MemoryStream ms = new MemoryStream())
        {
            Document doc = new Document();
            PdfWriter writer = PdfWriter.GetInstance(doc, ms);

            doc.SetPageSize(PageSize.LETTER);
            doc.Open();
            PdfContentByte cb = writer.DirectContent;
            PdfImportedPage page;

            PdfReader reader;
            foreach (byte[] p in pdfByteContent)
            {
                reader = new PdfReader(p);
                int pages = reader.NumberOfPages;

                // loop over document pages
                for (int i = 1; i <= pages; i++)
                {
                    doc.SetPageSize(PageSize.LETTER);
                    doc.NewPage();
                    page = writer.GetImportedPage(reader, i);
                    cb.AddTemplate(page, 0, 0);

                }
            }

            doc.Close();
            allBytes = ms.GetBuffer();
            ms.Flush();
            ms.Dispose();
        }

        return allBytes;
    }

Above is the working code that results in a single pdf being created, and the rest of the files are being ignored. Any suggestions

Answer 1

This is pretty much just a C# version of Bruno's code here.

This is pretty much the simplest, safest and recommended way to merge PDF files. The PdfSmartCopy object is able to detect redundancies in the multiple files which can reduce file size some times. One of the overloads on it accepts a full PdfReader object which can be instantiated however you want.

public static byte[] concatAndAddContent(List<byte[]> pdfByteContent) {

    using (var ms = new MemoryStream()) {
        using (var doc = new Document()) {
            using (var copy = new PdfSmartCopy(doc, ms)) {
                doc.Open();

                //Loop through each byte array
                foreach (var p in pdfByteContent) {

                    //Create a PdfReader bound to that byte array
                    using (var reader = new PdfReader(p)) {

                        //Add the entire document instead of page-by-page
                        copy.AddDocument(reader);
                    }
                }

                doc.Close();
            }
        }

        //Return just before disposing
        return ms.ToArray();
    }
}