Creating a global App.xaml

In all Xamarin.Forms projects we must create an Application file that inherits the Application class. We are going to extend this Application file and create a global resource dictionary. If you came from WPF you will recognize the use of a global resource dictionary that we can reference in all XAML sheets. This global resource dictionary is kept in the App.xaml file. It will have references to different converters, styles, and data templates. Rather than declaring static resource dictionaries at the top of every ContentPage or ContentView, we want to create only one dictionary that every XAML interface can access. This means we only create one dictionary at startup throughout the entire life of the application, rather than creating multiple dictionaries on views when they are displayed.

Let's create a new ContentPage, call it App.xaml, and place it in the Stocklist.XamForms project. We can now remove the App.cs file that already exists in this project. Inside...