async void EditButtonClickedAsync(object sender, EventArgs e)
{
// BindingContext as EventViewModel
var editPage = new PostEditPage(BindingContext as PostViewModel);
await Navigation.PushAsync(editPage);
}
async void AddButtonClickedAsync(object sender, EventArgs e)
{
var editPage = new PostEditPage(new PostViewModel(null));
// var editPage = new EventEditPage();
await Navigation.PushAsync(editPage);
}