UIView contentView = new UIView();
contentView.Frame = new RectangleF(new PointF(0,0), new SizeF(200, 200));
contentView.BackgroundColor = UIColor.White;
UIButton contentButton = new UIButton();
contentButton.SetTitle("This is a pretty Button", UIControlState.Normal);
contentButton.Frame = new RectangleF(new PointF(10, 10), new SizeF(contentView.StringSize(contentButton.TitleLabel.Text, contentButton.Font)));
contentButton.SetTitleColor(UIColor.Black, UIControlState.Normal);
contentButton.TouchUpInside += delegate(object sender, EventArgs e) {
    DismissModalViewControllerAnimated(true);
};
contentView.AddSubview(contentButton);

UIViewController contentController = new UIViewController();
contentController.View = contentView;

UIToolbar toolBar = new UIToolbar();
toolBar.Frame = new RectangleF(new PointF(0,0), new SizeF(View.Frame.Width, 40));
View.AddSubview(toolBar);

UIBarButtonItem barButton = new UIBarButtonItem();
barButton.Title = "Open Popover";
barButton.Style = UIBarButtonItemStyle.Bordered;
barButton.Clicked += delegate(object sender, EventArgs e) {
    UIPopoverController popup = new UIPopoverController(contentController);
    popup.SetPopoverContentSize(new SizeF(contentController.View.Frame.Width, contentController.View.Frame.Height), true);
    popup.PresentFromBarButtonItem((UIBarButtonItem)sender, UIPopoverArrowDirection.Any, true);
};

UIBarButtonItem barButton2 = new UIBarButtonItem();
barButton2.Title = "Open ModalView";
barButton2.Style = UIBarButtonItemStyle.Bordered;
barButton2.Clicked += delegate(object sender, EventArgs e) {
    contentButton.SetTitle("Close Modal Popup", UIControlState.Normal);
    contentController.ModalPresentationStyle = UIModalPresentationStyle.FormSheet;
    contentController.ModalTransitionStyle = UIModalTransitionStyle.CoverVertical;
    contentController.ModalInPopover = true;
    PresentModalViewController(contentController, true);
};

toolBar.Items = new UIBarButtonItem[] { barButton, barButton2 };