public override void OnNavigatedFrom(NavigationParameters parameters)
 {
     base.OnNavigatedFrom(parameters);
     TodoCollection = TodoRN.ListarTarefas();
 }
 public override void OnNavigatingTo(NavigationParameters parameters)
 {
     base.OnNavigatingTo(parameters);
     Title          = "Lista de Tarefas";
     TodoCollection = TodoRN.ListarTarefas();
 }