UIViewController+AddSearchController

using System;
using UIKit;

namespace App.iOS.Extensions
{
    public static class UIViewController_AddSearchController
    {
        public static UISearchController AddSearchController(this UIViewController @this)
        {
            var searchController = new UISearchController(null as UIViewController);
            searchController.SearchResultsUpdater = @this as IUISearchResultsUpdating ?? 
                                                    throw new IUISearchResultsUpdatingNotImplementedException(@this);
            searchController.ObscuresBackgroundDuringPresentation = false;
            searchController.SearchBar.Placeholder = "Buscar";
            @this.NavigationItem.SearchController = searchController;
            @this.NavigationItem.HidesSearchBarWhenScrolling = false;
            @this.DefinesPresentationContext = true;

            return searchController;
        }

        private class IUISearchResultsUpdatingNotImplementedException : Exception
        {
            public ControllerNaoImplementaBarraDeBuscaException(UIViewController controller) : 
                base ($"Controller {controller.GetType().Name} deve implementar interface {typeof(IUISearchResultsUpdating).Name}")
            {}
        }
    }
}