How to convert a byte array to a pdf

The big question is, what on earth is this byte array in the first place ? Is it an image file ? Is it text ? Either way you need some sort of PDF library to do this, but your question is harder to answer than most PDF questions, because the answer depends on what data you're working with, to a degree ( it will still be 'find a library and buy it, tho )

To do this you need ITextSharp.

Just download it and use to create PDF document:

Document myDocument = new Document(PageSize.LETTER);
PdfWriter.GetInstance(myDocument, new FileStream("mydocument.pdf", FileMode.Create));
myDocument.Open();
myDocument.Add(new Paragraph(Encoding.UTF8.GetString(bytes)));
myDocument.Close()

:)

Create a RAM-drive at runtime, save the bytes to that virtual drive with a PDF extension, then have Adobe Reader open that virtual file.

Either that, or create your own viewer or find a PDF viewer that accepts memory content or a stream.