Windows Phone apps often consist of many pages and, in turn, many viewmodels. It is useful to employ a viewmodel base class to share common infrastructure across all viewmodels in your app.
In the samples throughout this book, most viewmodels subclass a custom
ViewModelBase class that provides, among other things, navigation support, error validation, state preservation, and property change notification (see Figure 2.9). Each of these capabilities is discussed alongside related topics in subsequent chapters.
ViewModelBase inherits from a custom
NotifyPropertyChangeBase class, which provides ...