As per .NET and Xamarin Forms guidelines, ViewModels usually implement the
INotifyPropertyChanged interface to inform the view of changes to the data model. This involves a lot of boilerplate, so Geocortex Mobile has a class,
NotifyPropertyBase, which handles the boilerplate and simplifies your code.
The ViewModel of the progress bar custom component is a good example of this pattern.
INotifyPropertyChanged for you and provides a helper function,
SetProperty. This helper function will ensure that
OnPropertyChanged is called if the value has changed and that the underlying field is set.
The Geocortex Mobile SDK Samples has an example of a breadcrumbs component that uses a viewmodel.