private async void _facebookButton_Clicked(object sender, EventArgs e) { DisableControls(); try { IFacebookButton facebook = DependencyService.Get <IFacebookButton> (); facebook.LoginWithReadPermissions(new string[] { "email" }, async(d) => { if (d == null) { EnableControls(); DisplayAlert(AppConfig.ApplicationName, "Facebook acount was not linked", "OK"); return; } await _parseService.LoginWithFacebook(d.UserId, d.AccessToken, d.TokenExpiration, s => FacebookLoginCallback(s)); }); } catch (Exception ex) { string er = ex.Message; } }