You can use the C1PdfViewer control in MVVM applications by binding its Source property to some public property from your View Model. The Source should be bound to a property of type Uri.

For example, add a property to your View Model named "SourceUri" of type Uri:

 public Uri SourceUri {
get; set; }

 In XAML, you would bind the C1PdfViewer to this property like this:

<c1:C1PdfViewer x:Name="pdfViewer" Source="{Binding SourceUri}" />