public void ShareImageOnFacebook(string caption, string imagePath)
        {
            SharePhoto tt = SharePhoto.From(new UIImage(imagePath), true);

            tt.Caption = caption;
            SharePhotoContent content = new SharePhotoContent();

            content.Photos = new SharePhoto[] { tt };
            content.SetContentUrl(new NSUrl(imagePath));

            var shareDelegate = new FbDelegate();

            var dialog = new ShareDialog();

            dialog.Mode = ShareDialogMode.FeedBrowser;
            dialog.SetDelegate(shareDelegate);
            dialog.SetShareContent(content);
            dialog.FromViewController = UIApplication.SharedApplication.KeyWindow.RootViewController;

            bool isInstalled = UIApplication.SharedApplication.CanOpenUrl(new NSUrl(urlString: "fb://"));

            if (isInstalled)
            {
                dialog.Mode = ShareDialogMode.Native;
                dialog.Show();
            }
            else
            {
                ShareAPI.Share(content, shareDelegate);
            }
        }
        public void ShareLinkOnFacebook(string text, string description, string link)
        {
            ShareLinkContent link1 = new ShareLinkContent();

            link1.SetContentUrl(new NSUrl(link));
            var shareDelegate = new FbDelegate();

            var dialog = new ShareDialog();

            dialog.Mode = ShareDialogMode.FeedBrowser;
            dialog.SetDelegate(shareDelegate);
            dialog.SetShareContent(link1);
            dialog.FromViewController = UIApplication.SharedApplication.KeyWindow.RootViewController;
            bool isInstalled = UIApplication.SharedApplication.CanOpenUrl(new NSUrl(urlString: "fb://"));

            if (isInstalled)
            {
                dialog.Mode = ShareDialogMode.Native;
                dialog.Show();
            }
            else
            {
                ShareAPI.Share(link1, shareDelegate);
            }
        }
        public void ShareTextOnFacebook(string text)
        {
            ShareLinkContent link = new ShareLinkContent();
            var shareDelegate     = new FbDelegate();

            var dialog = new ShareDialog();

            dialog.Mode = ShareDialogMode.Native;
            dialog.SetDelegate(shareDelegate);
            dialog.SetShareContent(link);
            dialog.FromViewController = UIApplication.SharedApplication.KeyWindow.RootViewController;
            bool isInstalled = UIApplication.SharedApplication.CanOpenUrl(new NSUrl(urlString: "fb://"));

            if (isInstalled)
            {
                dialog.Show();
            }
            else
            {
                new UIAlertView("Error", "Cannot share text when app is not installed", null, "Ok", null).Show();
            }
        }