public IActionResult Detail(int id)
        {
            Activities theActivity = context.Activities
                                     .Single(e => e.Id == id);


            ActivitiesDetailViewModel viewModel = new ActivitiesDetailViewModel(theActivity);

            return(View(viewModel));
        }
        public ActivitiesDetailPage(ActivitiesDetailViewModel viewModel)
        {
            InitializeComponent();

            BindingContext = viewModel;
        }