I have written a code for previewing a PDF file in Xamarin IOS. Now how can i annotate this PDF in Xamarin IOS using this QuickLook framework?

Question

UIViewController currentController = UIApplication.SharedApplication.KeyWindow.RootViewController;
while (currentController.PresentedViewController != null)
    currentController = currentController.PresentedViewController;
UIView currentView = currentController.View;
QLPreviewController preview = new QLPreviewController();
QLPreviewItem item = new QLPreviewItemBundle(fileData.FileName, fileData.FilePath);
preview.DataSource = new PreviewControllerDS(item);

currentController.PresentViewController(preview, true, null);

Answer 1

To begin, create a class that inherits from QLPreviewControllerDataSource.

public class QuickLookSource : QLPreviewControllerDataSource
{
    List documents;

    public QuickLookSource(List docs)
    {
        documents = docs;
    }

    public override nint PreviewItemCount(QLPreviewController controller)
    {
        return documents.Count;
    }

    public override IQLPreviewItem GetPreviewItem(QLPreviewController controller, nint index)
    {
        return new PreviewItem(documents[(int)index]);
    }
}

public class PreviewItem : QLPreviewItem
{
    NSUrl fileUrl;

    public override NSUrl ItemUrl => fileUrl;
    public override string ItemTitle => fileUrl.LastPathComponent;

    public PreviewItem(string url)
    {
        fileUrl = NSUrl.FromFilename(url);
    }
}

Then to present a preview, create a new QLPreviewController and set DataSource to you data source class. Since the controller can preview multiple files, make sure to set CurrentPreviewItemIndex before navigating to the controller:

var previewController = new QLPreviewController();
previewController.DataSource = new QuickLookSource(source.Documents);

previewController.CurrentPreviewItemIndex = indexPath.Row;
NavigationController.PushViewController(previewController, true);

// You can present modally instead
// PresentViewController(previewController, true, null);