In this example, the page's BindingContext property is set to the PersonCollectionViewModel. The following example shows the XAML that consumes the PersonCollectionViewModel: These properties are all set when the class is first created and do not change. In this example, changes to the three ICommand properties and the Persons property do not result in Propert圜hanged events being raised. Propert圜hanged?.Invoke(this, new Propert圜hangedEventArgs(propertyName)) Protected void OnPropert圜hanged( string propertyName = null) To use the command interface, your viewmodel should contain properties of type ICommand: public ICommand M圜ommand = new ObservableCollection() īool SetProperty(ref T storage, T value, string propertyName = null) Public event EventHandler CanExecuteChanged Public bool CanExecute (Object parameter) The ICommand interface is defined in the namespace, and consists of two methods and one event: public interface ICommand All these commands can be handled within a viewmodel using an approach that doesn't depend on the user-interface object in the view. Many other views also define Command and CommandParameter properties. You can set the CommandParameter property to arbitrary data to distinguish between multiple buttons if they are all bound to the same ICommand property in the viewmodel. The viewmodel contains code associated with that ICommand property that is executed when the button is clicked. To use the command interface, you define a data binding that targets the Command property of the Button where the source is a property in the viewmodel of type ICommand.

To allow a data binding between a Button and a viewmodel, the Button defines two properties: Data bindings are defined between these commands and the Button. The viewmodel can contain commands, which are methods that are executed in reaction to a specific activity in the view such as a Button click. The commanding interface provides an alternative approach to implementing commands that is much better suited to the MVVM architecture. These commands are generally signaled by button clicks or finger taps, and traditionally they are processed in the code-behind file in a handler for the Clicked event of the Button or the Tapped event of a TapGestureRecognizer. Sometimes an app has needs that go beyond these property bindings by requiring the user to initiate commands that affect something in the viewmodel. NET Multi-platform App UI (.NET MAUI) app that uses the Model-View-ViewModel (MVVM) pattern, data bindings are defined between properties in the viewmodel, which is typically a class that derives from INotifyPropert圜hanged, and properties in the view, which is typically the XAML file.

ICommand by Dave Lewis