Add text annotation to a document with Xamarin viewer

To add a sticky note (text annotation) to a PDF Document.

PDFDoc doc = new PDFDoc(filename);
Page page = doc.GetPage(1);

// Create the sticky note (Text annotation)
Text txt = Text.Create(doc, new Rect( 10, 20, 30, 40 ));
txt.SetIcon("UserIcon");
txt.SetContents("The quick brown fox ate the lazy mouse.");
txt.SetColor(new ColorPt(0,1,0));
txt.RefreshAppearance();
page.AnnotPushBack(txt);

Add or edit PDF annotations
Full code sample which shows how to add or edit PDF annotations (e.g. hyperlink, intra-document link, stamp, rubber stamp, file attachment, sound, text, free-text, line, circle, square, polygon, polyline, highlight, squiggly, caret, and ink).