How to activate an app (XAML)
Learn how to handle activation for your app. The example in this topic overrides the OnLaunched method.
Roadmap: How does this topic relate to others? See:
- Roadmap for Windows Runtime apps using C# or Visual Basic
- Roadmap for Windows Runtime apps using C++
The Windows.UI.Xaml.Application class defines methods you can override to handle the various activation types. Several of the activation types have a specific method that you can override. For the other activation types, override the OnActivated method.
Define the class for your application.
<Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="AppName.App" >
Note On Windows Phone, this method is called each time the user launches the app from Start tile or app list, even when the app is currently suspended in memory. On Windows, launching a suspended app from Start tile or app list doesn’t call this method.
Class App Protected Overrides Sub OnLaunched(args As LaunchActivatedEventArgs) Window.Current.Content = New MainPage() Window.Current.Activate() End Sub End Class
When the user switches to your terminated app, the system sends the Activated event, with Kind set to Launch and PreviousExecutionState set to Terminated or ClosedByUser. The app should load its saved application data and refresh its displayed content.
Protected Overrides Sub OnLaunched(args As Windows.ApplicationModel.Activation.LaunchActivatedEventArgs) Dim restoreState As Boolean = False Select Case args.PreviousExecutionState Case ApplicationExecutionState.Terminated ' TODO: Populate the UI with the previously saved application data restoreState = True Case ApplicationExecutionState.ClosedByUser ' TODO: Populate the UI with the previously saved application data restoreState = True Case Else ' TODO: Populate the UI with defaults End Select Window.Current.Content = New MainPage(restoreState) Window.Current.Activate() End Sub
If the value of PreviousExecutionState is NotRunning, the app failed to save its application data successfully and the app should start over as if it were being initially launched.
On Windows Phone, the Resuming event is always followed by OnLaunched, even when your app is currently suspended and the user re-launches your app from a primary tile or app list. Apps can skip initialization if there is already content set on the current window. You can check the LaunchActivatedEventArgs.TileId property to determine if the app was launched from a primary or a secondary tile and, based on that information, decide whether you should present a fresh or resume app experience.
- How to suspend an app
- How to resume an app
- Application lifecycle
- Guidelines for app suspend and resume