Modifying the MainPage

We will be replacing the entire contents of the MainPage and adding a reference to the WhackABox.Controls namespace so that we can use the ARView control. Let's set this up by going through the following steps:

1. In the WhackABox project, open the MainPage.xaml file.
2. Edit the XAML code to look like the following code. The XAML in bold represents the new elements that must be added:

<?xml version="1.0" encoding="utf-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
           xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
           xmlns:local="clr-namespace:WhackABox" 
           xmlns:controls="clr-namespace:WhackABox.Controls"
           x:Class="WhackABox.MainPage">
     
<Grid>
   <Grid.ColumnDefinitions>
      <ColumnDefinition Width="*" />
      <ColumnDefinition Width="*" />
   </Grid.ColumnDefinitions...