Fixing the code behind

Now that the XAML is complete, we have some work to do in the code behind. We'll start by adding some using statements:

1. Open the ChatView.xaml.cs file.
2. Add using statements for Chat.ViewModels, Xamarin.Forms, and Xamarin.Forms.PlatformConfiguration.iOSSpecific.
3. Add a private field called viewModel of the ChatViewModel type, which will hold a local reference to ChatViewModel.

The class should now look as follows. The code in bold indicates what should have changed:

using System.Linq;
using Chat.ViewModels;
using Xamarin.Forms;
using Xamarin.Forms.PlatformConfiguration.iOSSpecific;

namespace Chat.Views
{
    public partial class ChatView : ContentPage
    {
        private ChatViewModel viewModel;
    
        public ChatView()
        {
            InitializeComponent();
        }
    }
}

When a new message arrives, this will be added to the Messages collection in ChatViewModel. To make sure that CollectionView scrolls appropriately so...