UWP: Simple Events

Notes

[07/19/2018] Note: This post refers to the library Microsoft.NETCore.UniversalWindowsPlatform, version 6.2.0-Preview1-26502-02.

Events

Some problems are just made so much easier in XAML based apps if you use the Event pub/sub model.

We’ll structure our events the way the excellent Template10 does:

One event
One EventRaised method

Untyped Events

These events carry no information aside form the fact that it occurred.

In the class that the event originates from:

public class MyEventPublisherClass {

    /* This the event that will be subscribed to. */
    public event EventHandler MyEvent;

    /* This is a convenience function that calls the event. */
    void RaiseMyEvent() => MyEvent?.Invoke(this, new EventArgs { });
}

This is an untyped event, so we use the Event version of an empty constructor with the new EventArgs {} syntax. The base EventArgs class contains no other fields.

In the class that you wish to receive event notifications from:

class MyEventSubscriberClass {

    public MyEventSubscriberClass() {
        /* Somewhere, usually in the constructor, we subscribe to the event*/
        MyEventPublisherClass.MyEvent += OnMyEventMethod;
    }

    /* This is the method that gets called when the event is triggerd */
    private void OnMyEventMethod(object sender, EventArgs e) {
        // Do Something
    }

}

Typed Events

These events carry additional, arbitrary information of your choice.

public class MyTypedEventPublisherClass {

    public event EventHandler<string> MyTypedEvent;
    void RaiseMyTypedEvent(string value) => MyTypedEvent?.Invoke(this, value);
}

class MyTypedEventSubscriberClass {

    public MyTypedEventSubscriberClass  () {
        MyTypedEventPublisherClass.MyTypedEvent += OnMyTypedEventMethod;
    }

    private void OnMyTypedEventMethod(object sender,  string e) {
        // Do something
    }
}

UWP event routing