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README.md

README.md

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sample
csharp
cpp
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windows-uwp

Background task sample

Shows how to create and register background tasks using the Windows Runtime background task API.

Note: This sample is part of a large collection of UWP feature samples. If you are unfamiliar with Git and GitHub, you can download the entire collection as a ZIP file, but be sure to unzip everything to access shared dependencies. For more info on working with the ZIP file, the samples collection, and GitHub, see Get the UWP samples from GitHub. For more samples, see the Samples portal on the Windows Dev Center.

A background task is triggered by a system or time event and can be constrained by one or more conditions. When a background task is triggered, its associated handler runs and performs the work of the background task. A background task can run even when the app that registered the background task is suspended.

This sample demonstrates the following:

  • Creating and registering background tasks written in C++, C#, or JavaScript.
  • Creating a background task that is triggered by a system event.
  • Requesting the user's permission to add the app to the lock screen.
  • Creating a background task that is triggered by a time trigger.
  • Adding a condition that constrains the background task to run only when the condition is in effect.
  • Creating and signaling an application trigger.
  • Reporting background task progress and completion to the app.
  • Using a deferral object to include asynchronous code in your background task.
  • Handling the cancellation of a background task, and ensuring the task is cancelled when required conditions are no longer met.
  • Initializing background task progress and completion handlers when the app is launched.
  • Registering a background task in a Background Task Registration Group.

To obtain an evaluation copy of Windows 8.1, go to Windows 8.1.

To obtain an evaluation copy of Microsoft Visual Studio 2013, go to Visual Studio 2013.

Note  For Windows 8 app samples, download the Windows 8 app samples pack. The samples in the Windows 8 app samples pack will build and run only on Microsoft Visual Studio 2012.

Related topics

Samples

Background Activation
Traffic App sample

Reference

Displaying tiles on the lock screen
Launching, resuming, and multitasking
Managing background tasks
Support your app with background tasks
Windows 8 app samples

API reference

Windows.ApplicationModel.Background (XAML)
Windows.UI.WebUI.WebUIBackgroundTaskInstance (HTML)

Related technologies

Windows.ApplicationModel.Background

Operating system requirements

Client

Windows 10

Server

None supported

Phone

Windows Phone 10

Build the sample

  1. If you download the samples ZIP, be sure to unzip the entire archive, not just the folder with the sample you want to build.
  2. Start Microsoft Visual Studio 2017 and select File > Open > Project/Solution.
  3. Starting in the folder where you unzipped the samples, go to the Samples subfolder, then the subfolder for this specific sample, then the subfolder for your preferred language (C++, C#, or JavaScript). Double-click the Visual Studio Solution (.sln) file.
  4. Press Ctrl+Shift+B, or select Build > Build Solution.

Run the sample

Deploying the sample

  1. Select Build > Deploy Solution.

Deploying and running the sample

  1. To debug the sample and then run it, press F5 or select Debug > Start Debugging. To run the sample without debugging, press Ctrl+F5 or selectDebug > Start Without Debugging.

Triggering background tasks

To trigger the background tasks associated with the TimeZoneChange event:

  1. Change date and time settings.
  2. Click Change time zone...
  3. Select a time zone that has a UTC offset different from the currently selected time zone.
  4. Click OK.

Background tasks associated with the TimeTrigger event will only fire if the app is currently on the lock screen. There are two ways to accomplish this.

Accept the initial request to add the BackgroundTaskSample app to the lock screen:

  1. Launch the BackgroundTaskSample app for the first time.
  2. Register the TimeTrigger event.
  3. Accept the request to add the BackgroundTaskSample app to the lock screen.

Add the BackgroundTaskSample app to the lock screen manually:

  1. From the Start screen, go to Settings > Customize your lock screen.
  2. Choose the BackgroundTaskSample app for the lock screen.
  3. Launch the BackgroundTaskSample app and register the TimeTrigger event.

Note  The minimum delay for creating TimeTrigger events is 15 minutes. The first timer event, however, might not occur until 15 minutes after it is expected to expire (30 minutes after the app registers the event).

Read more

See the following topics for step-by-step information about using background tasks:

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