private async void share()
        {
            string text = _viewModel.ToString();

            var s = await DisplayActionSheet("Condividi", "Annulla", null, "Visualizza PDF", "Condividi PDF", "Condividi Testo");

            if (s.Contains("PDF"))
            {
                PdfFile pdf = new PdfFile()
                {
                    Title = "Orario Giornaliero", TitleFacolta = _viewModel.LaureaString, TitleInfo = _viewModel.DataString, Text = string.Join("\n", _viewModel.ListOrari)
                };
                pdf.CreateGiornaliero();

                await pdf.Save();

                if (s.Contains("Condividi"))                //Condividi PDF
                {
                    DependencyService.Get <IFile> ().Share(pdf._filename);
                }
                else
                {
                    await pdf.Display();                      //visualizza PDF
                }
            }
            else
            {
                text += Settings.Firma;
                DependencyService.Get <IMethods> ().Share(text);                 //condividi testo
            }

            //Insights.Track("Share", new Dictionary <string,string>{
            //	{"Orario", "Giornaliero_" + s},
            //});
        }