void OnItemSelected(object sender, SelectedItemChangedEventArgs e)
{
var todoItem = e.SelectedItem as TodoItem;
var todoPage = new TodoItemPage();
todoPage.BindingContext = todoItem;
Navigation.PushAsync(todoPage);
}
void OnAddItemClicked(object sender, EventArgs e)
{
var todoItem = new TodoItem()
{
ID = Guid.NewGuid().ToString()
};
var todoPage = new TodoItemPage(true);
todoPage.BindingContext = todoItem;
Navigation.PushAsync(todoPage);
}