Interacting with the UI from the view model without breaking MVVM

Commands help you invoke a method in a view model when some action is executed in the UI. However, sometimes you may need to perform the opposite task: call a method in a UI control when some logic is executed in your view model. For example, let’s assume, you need to scroll CollectionView down each time a user adds a new item to the bound collection in the view model. Let’s see how to accomplish this task using WeakReferenceMessenger, available in CommunityToolkit.Mvvm.

Definition

WeakReferenceMessenger enables communication between different parts of an application without creating strong references between objects. Weak references allow you to avoid memory leaks even if you don’t unregister a message handler.

Getting ready

Start with the project you got after executing the fourth recipe of this chapter: Initializing bound collections without freezing the UI. This project is available...