public BoletasViewModel() { Title = "Browse"; Boletas = new ObservableCollection <Boleta>(); LoadItemsCommand = new Command(async() => await ExecuteLoadItemsCommand()); MessagingCenter.Subscribe <NewItemPage, Boleta>(this, "AddItem", async(obj, item) => { var _item = item as Boleta; Boletas.Add(_item); await DataStore.AddBoletaAsync(_item); }); }