Coding4Fun

Calling the InnerTubeService Class

Now that we have our classes designed, let's show how we can convert the XML from Figure 4-4 into the objects represented in Figure 4-5. To do this, we'll use another class, our InnerTubeService class. As you can see in Figure 4-6, the common feeds—Top Rated, Most Viewed, etc.—from YouTube's API are all available as methods. The return type for all of the methods in InnerTubeService is an ObservableCollection<Inner TubeVideo>.

Figure 4-6. IntelliSense showing the available methods for retrieving YouTube data

Why Use ObservableCollection?

One thing to note here is that the collection data type for videos is an ObservableCollection. The ObservableCollection is just like a Collection class, but it implements a couple of events, CollectionChanged and PropertyChanged, respectively, that enable it to easily update data bound data sources in WPF. We'll get into data-binding in the Dissecting MainWindow.xaml section later in the chapter, but the point here is that we use this particular type because it will automatically update our UI elements when the collection changes, without us needing to rebind the data.

Converting YouTube XML into .NET Objects

The InnerTubeService class actually has only one real method that does the work of converting XML into objects, and that's the ConvertYouTubeXmlIntoObjects method. The reason for this is that each YouTube XML API ...