title: Xamarin Forms "...DisplayAlert does not exist in the current context."
body: <p>I'm working with Xamarin, still new to it, but I'm having a problem that I get the feeling I shouldn't be. Here's my problem:</p>
  
  <pre><code>using System;
  using Xamarin.Forms;
  
  namespace DataBinding_Lists
  {
  public class App
  {
      public static Page GetMainPage ()
      {   
          var listView = new ListView { RowHeight = 40 };
          listView.ItemsSource = new Person []
          {
              new Person { FirstName = "Abe", LastName = "Lincoln" },
              new Person { FirstName = "Groucho", LastName = "Marks" },
              new Person { FirstName = "Carl", LastName = "Marks" },
          };
  
          listView.ItemTemplate = new DataTemplate(typeof(TextCell));
          listView.ItemTemplate.SetBinding(TextCell.TextProperty, "FirstName");
          listView.ItemSelected += async (sender, e) =&gt; {
              await DisplayAlert ("Tapped!", e.SelectedItem + " was tapped.", "OK", "");
          };
  
          return new ContentPage { 
              Content = new StackLayout
              {
                  Padding = new Thickness (5,20,5,5),
                  Spacing = 10,
                  Children = { listView }
              }
          };
      }
  
  }
  </code></pre>
  
  <p>}</p>
  
  <p>Obviously, I've got a class on another page called "Person." This class has two properties: "FirstName" and "LastName." When I try and put all of this together like so in Xamarin, I get the error saying: "The name 'DisplayAlert' does not exist in the current context."</p>