private async void GetUsers() { var temp = await FBClient .Child("users") .OrderByKey() .OnceAsync <UserModel>(); await App.Current.Dispatcher.BeginInvoke((Action) delegate() { DbUsers.Clear(); }); foreach (var e in temp) { await App.Current.Dispatcher.BeginInvoke((Action) delegate() { DbUsers.Add(new UserModel { Key = e.Key, Name = e.Object.Name }); }); } //await App.Current.Dispatcher.BeginInvoke((Action)delegate () { StrCollection.Clear(); }); //foreach (var e in temp) //{ // await App.Current.Dispatcher.BeginInvoke((Action)delegate () // { // StrCollection.Add(e.Object.Name); // }); //} }