Handle app activation
Learn how to handle app activation by overriding the Application.OnLaunched method.
Note
For info about handling activation in a desktop app, see Get activation info for packaged apps. Also see AppLifecycle—rich activation on GitHub.
Override the launch handler
When an app is activated, for any reason, the system sends the CoreApplicationView.Activated event. For a list of activation types, see the ActivationKind enumeration.
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
x:Class="AppName.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
Override the OnLaunched method. This method is called whenever the user launches the app. The LaunchActivatedEventArgs parameter contains the previous state of your app and the activation arguments.
Note
On Windows, launching a suspended app from Start tile or app list doesn't call this method.
using System;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
namespace AppName
{
public partial class App
{
async protected override void OnLaunched(LaunchActivatedEventArgs args)
{
EnsurePageCreatedAndActivate();
}
// Creates the MainPage if it isn't already created. Also activates
// the window so it takes foreground and input focus.
private MainPage EnsurePageCreatedAndActivate()
{
if (Window.Current.Content == null)
{
Window.Current.Content = new MainPage();
}
Window.Current.Activate();
return Window.Current.Content as MainPage;
}
}
}
Class App
Protected Overrides Sub OnLaunched(args As LaunchActivatedEventArgs)
Window.Current.Content = New MainPage()
Window.Current.Activate()
End Sub
End Class
...
#include "MainPage.h"
#include "winrt/Windows.ApplicationModel.Activation.h"
#include "winrt/Windows.UI.Xaml.h"
#include "winrt/Windows.UI.Xaml.Controls.h"
...
using namespace winrt;
using namespace Windows::ApplicationModel::Activation;
using namespace Windows::UI::Xaml;
using namespace Windows::UI::Xaml::Controls;
struct App : AppT<App>
{
App();
/// <summary>
/// Invoked when the application is launched normally by the end user. Other entry points
/// will be used such as when the application is launched to open a specific file.
/// </summary>
/// <param name="e">Details about the launch request and process.</param>
void OnLaunched(LaunchActivatedEventArgs const& e)
{
Frame rootFrame{ nullptr };
auto content = Window::Current().Content();
if (content)
{
rootFrame = content.try_as<Frame>();
}
// Do not repeat app initialization when the Window already has content,
// just ensure that the window is active
if (rootFrame == nullptr)
{
// Create a Frame to act as the navigation context and associate it with
// a SuspensionManager key
rootFrame = Frame();
rootFrame.NavigationFailed({ this, &App::OnNavigationFailed });
if (e.PreviousExecutionState() == ApplicationExecutionState::Terminated)
{
// Restore the saved session state only when appropriate, scheduling the
// final launch steps after the restore is complete
}
if (e.PrelaunchActivated() == false)
{
if (rootFrame.Content() == nullptr)
{
// When the navigation stack isn't restored navigate to the first page,
// configuring the new page by passing required information as a navigation
// parameter
rootFrame.Navigate(xaml_typename<BlankApp1::MainPage>(), box_value(e.Arguments()));
}
// Place the frame in the current Window
Window::Current().Content(rootFrame);
// Ensure the current window is active
Window::Current().Activate();
}
}
else
{
if (e.PrelaunchActivated() == false)
{
if (rootFrame.Content() == nullptr)
{
// When the navigation stack isn't restored navigate to the first page,
// configuring the new page by passing required information as a navigation
// parameter
rootFrame.Navigate(xaml_typename<BlankApp1::MainPage>(), box_value(e.Arguments()));
}
// Ensure the current window is active
Window::Current().Activate();
}
}
}
};
using namespace Windows::ApplicationModel::Activation;
using namespace Windows::Foundation;
using namespace Windows::UI::Xaml;
using namespace AppName;
void App::OnLaunched(LaunchActivatedEventArgs^ args)
{
EnsurePageCreatedAndActivate();
}
// Creates the MainPage if it isn't already created. Also activates
// the window so it takes foreground and input focus.
void App::EnsurePageCreatedAndActivate()
{
if (_mainPage == nullptr)
{
// Save the MainPage for use if we get activated later
_mainPage = ref new MainPage();
}
Window::Current->Content = _mainPage;
Window::Current->Activate();
}
Restore application data if app was suspended then terminated
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.
async protected override void OnLaunched(LaunchActivatedEventArgs args)
{
if (args.PreviousExecutionState == ApplicationExecutionState.Terminated ||
args.PreviousExecutionState == ApplicationExecutionState.ClosedByUser)
{
// TODO: Populate the UI with the previously saved application data
}
else
{
// TODO: Populate the UI with defaults
}
EnsurePageCreatedAndActivate();
}
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
void App::OnLaunched(Windows::ApplicationModel::Activation::LaunchActivatedEventArgs const& e)
{
if (e.PreviousExecutionState() == ApplicationExecutionState::Terminated ||
e.PreviousExecutionState() == ApplicationExecutionState::ClosedByUser)
{
// Populate the UI with the previously saved application data.
}
else
{
// Populate the UI with defaults.
}
...
}
void App::OnLaunched(Windows::ApplicationModel::Activation::LaunchActivatedEventArgs^ args)
{
if (args->PreviousExecutionState == ApplicationExecutionState::Terminated ||
args->PreviousExecutionState == ApplicationExecutionState::ClosedByUser)
{
// TODO: Populate the UI with the previously saved application data
}
else
{
// TODO: Populate the UI with defaults
}
EnsurePageCreatedAndActivate();
}
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.
Remarks
Note
Apps can skip initialization if there is already content set on the current window. You can check the LaunchActivatedEventArgs.TileId property to determine whether 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.