Hello,
I downloaded your code for Syncfusion Xamarin UI Controls from https://github.com/syncfusion/xamarin-demos
And then built SampleBrowser.PdfViewer successfully.
There is one strange thing which I don't understand.
In the first tab that opens "GIS Succinctly.pdf", I am not able to use the below code to annotate a text. But the same 2 lines of code works in the 3rd tab "Annotations.pdf". It annotates the text. I don't know what am I missing here. How do I annotate text in the first document?
TextMarkupAnnotation annotation = new TextMarkupAnnotation(TextMarkupAnnotationType.Highlight, 1, 20, 30);
pdfViewerControl.AddAnnotation(annotation);
PS: The above code annotates in page number 1. In case of "GIS Succinctly.pdf" you would need to change the page number to 2 or 3 to check because there is no text in the first page.