App Center Distribute – Xamarin In-app updates

App Center Distribute will let your users install a new version of the app when you distribute it via App Center. With a new version of the app available, the SDK will present an update dialog to the users to either download or postpone the new version. Once they choose to update, the SDK will start to update your application.

Warning

Google Play considers the in-app update code as malicious behavior even if it isn’t used at runtime. Use a variant of the Distribute SDK as directed in this section before submitting your app to Google Play. Failure to not remove the in-app update code can lead to noncompliance and removal of the app from Google Play.

Note

If you're running automated UI tests, enabled in-app updates will block your automated UI tests as they'll try to authenticate against the App Center backend. We recommend to not enable App Center Distribute for your UI tests.

Add in-app updates to your app

Follow the Get started section if you haven't set up and started the SDK in your application, yet.

1. Add the App Center Distribute module

The App Center SDK is designed with a modular approach – a developer only needs to integrate the modules of the services that they're interested in.

Visual Studio for Mac

  • Open Visual Studio for Mac.
  • Click File > Open and choose your solution.
  • In the solution navigator, right-click the Packages section, and choose Add NuGet packages....
  • Search for App Center, and install App Center Distribute.
  • Click Add Packages.

Visual Studio for Windows

  • Open Visual Studio for Windows.
  • Click File > Open and choose your solution.
  • In the solution navigator, right-click References and choose Manage NuGet Packages.
  • Search for App Center, and install Microsoft.AppCenter.Distribute.

Package Manager Console

  • Open the console in Visual Studio. To do this, choose Tools > NuGet Package Manager > Package Manager Console.
  • If you're working in Visual Studio for Mac, make sure you've installed the NuGet Package Management Extensions. For this, choose Visual Studio > Extensions, search for NuGet and install, if necessary.
  • Type the following command in the console:
Install-Package Microsoft.AppCenter.Distribute

Note

If you use the App Center SDK in a portable project (such as Xamarin.Forms), you must install the packages in each of the projects: the portable, Android, and iOS ones. To do that, you should open each sub-project and follow the corresponding steps described in Visual Studio for Mac or Visual Studio for Windows sections.

2. Start App Center Distribute

To use App Center, you must opt in to the module(s) that you want to use. By default, no modules are started and you must explicitly call each of them when starting the SDK.

2.1 Add App Center Distribute imports

Add the App Center Distribute imports before you get started with using Distribute module:

  • Xamarin.iOS - Open the project's AppDelegate.cs file and add the following lines below the existing using statements
  • Xamarin.Android - Open the project's MainActivity.cs file and add the following lines below the existing using statements
  • Xamarin.Forms - Open the project's App.xaml.cs file and add the following lines below the existing using statements
using Microsoft.AppCenter;
using Microsoft.AppCenter.Distribute;

2.2 Add the Start() method

Add Distribute to your Start() method to start App Center Distribute service.

Xamarin.iOS

Open the project's AppDelegate.cs file and add the Start() call inside the FinishedLaunching() method

Distribute.DontCheckForUpdatesInDebug();
AppCenter.Start("{Your Xamarin iOS App Secret}", typeof(Distribute));
Xamarin.Android

Open the project's MainActivity.cs file and add the Start() method call inside the OnCreate() method:

AppCenter.Start("{Your Xamarin Android App Secret}", typeof(Distribute));

To enable in-app updates for debug builds on Android, call the following method before AppCenter.Start:

Distribute.SetEnabledForDebuggableBuild(true);
Xamarin.Forms

To create a Xamarin.Forms app targeting both Android and iOS platforms, create two apps in the App Center portal - one for each platform. Creating two apps will give you two App secrets - one for Android and another one for iOS. Open the project's App.xaml.cs (or your class that inherits from Xamarin.Forms.Application) in the shared or portable project and add the Start() call inside the OnStart() override method.

AppCenter.Start("ios={Your Xamarin iOS App Secret};android={Your Xamarin Android App secret}", typeof(Distribute));

For your iOS application, open the AppDelegate.cs and add the following line before the call to LoadApplication:

Distribute.DontCheckForUpdatesInDebug();

This step isn't necessary on Android where the debug configuration is detected automatically at runtime.

To enable in-app updates for debug builds on Android, call the following method in the project's MainActivity.cs file, in the OnCreate method and before LoadApplication.

Distribute.SetEnabledForDebuggableBuild(true);

Note

This method only affects debug builds, and has no impact on release builds.

2.3 [For iOS only] Modify the project's Info.plist

App Center SDK checks urls redirecting to the application to avoid sideloading, so in order for updates distributed through the portal to be handled correctly, you'd need to specify CFBundleURLSchemes in CFBundleURLTypes section of Info.plist file:

Note

Info.plist, or an information property list file is a structured text file that contains essential configuration information for a bundled executable. You can find more information about it in Apple developer documentation.

  1. Add a new key for URL types or CFBundleURLTypes in your Info.plist file (in case Xcode displays your Info.plist as source code).
  2. Change the key of the first child item to URL Schemes or CFBundleURLSchemes.
  3. Enter appcenter-${APP_SECRET} as the URL scheme and replace ${APP_SECRET} with the App Secret of your app.

Tip

If you want to verify that you modified the Info.plist correctly, open it as source code. It should contain the following entry with your App Secret instead of ${APP_SECRET}:

<key>CFBundleURLTypes</key>
  <array>
      <dict>
          <key>CFBundleURLSchemes</key>
          <array>
              <string>appcenter-${APP_SECRET}</string>
          </array>
      </dict>
  </array>

Remove in-app updates for Google Play builds

Google Play considers the in-app update code as malicious behavior even if it isn’t used at runtime. Failure to not remove the in-app update code can lead to noncompliance and removal of the app from Google Play. To make it easier, we provide the version of App Center Distribute SDK with stubbed APIs, so the only change for you is a dependency swap.

  1. Add a new build configuration named GooglePlay for your Xamarin.Android project. Make sure that the project build configuration is correctly mapped to the appropriate solution configuration. See Visual Studio or Visual Studio for Mac instructions for more details.

  2. Open Xamarin.Android project's .csproj in any text editor and move distribute reference into the conditional item group:

    <ItemGroup Condition=" '$(Configuration)' != 'GooglePlay' ">
        <PackageReference Include="Microsoft.AppCenter.Distribute" Version="3.3.0" />
    </ItemGroup>
    <ItemGroup Condition=" '$(Configuration)' == 'GooglePlay' ">
        <PackageReference Include="Microsoft.AppCenter.DistributePlay" Version="3.3.0" />
    </ItemGroup>
    

    Note

    If you're using old packages.config format to manage NuGet references, you can migrate to a PackageReference format, follow the migration instruction.

  3. Save your changes and restore NuGet packages.

  4. You can change the configuration in the command bar at the top of the IDE.

Use private distribution group

By default, Distribute uses a public distribution group. If you want to use a private distribution group, you'll need to explicitly set it via UpdateTrack property.

Distribute.UpdateTrack = UpdateTrack.Private;

Note

The default value is UpdateTrack.Public. This property can only be updated before the AppCenter.Start method call. Changes to the update track aren't persisted when the application process restarts, and so if the property isn't always updated before the AppCenter.Start call, it will be public, by default.

After this call, a browser window will open up to authenticate the user. All the subsequent update checks will get the latest release on the private track. The update track isn't persisted in the SDK across app launches.

If a user is on the private track, it means that after the successful authentication, they'll get the latest release from any private distribution groups they're a member of. If a user is on the public track, it means that they'll get the latest release from any public distribution group.

Disable Automatic Check for Update

By default, the SDK automatically checks for new releases:

  • When the application starts.
  • When the application goes into background then in foreground again.
  • When enabling the Distribute module if previously disabled.

If you want to check for new releases manually, you can disable automatic check for update. To do this, call the following method before the SDK start:

Distribute.DisableAutomaticCheckForUpdate();

Note

This method must be called before the AppCenter.Start method call.

Then you can use the CheckForUpdate API which is described in the following section.

Manually Check for Update

Distribute.CheckForUpdate();

Note

A manual check for update call works even when automatic updates are enabled. A manual check for update is ignored if another check is already being done. The manual check for update won't be processed if the user has postponed updates (unless the latest version is a mandatory update).

Customize or localize the in-app update dialog

1. Customize or localize text

You can easily provide your own resource strings if you want to localize the text displayed in the update dialog. Look at the string files for iOS in this resource file and those for Android in this resource file. Use the same string name/key and specify the localized value to be reflected in the dialog in your own app resource files.

2. Customize the update dialog

You can customize the default update dialog's appearance by implementing the ReleaseAvailable callback. You need to register the callback before calling AppCenter.Start as shown in the following example:

// In this example OnReleaseAvailable is a method name in same class
Distribute.ReleaseAvailable = OnReleaseAvailable;
AppCenter.Start(...);

Here is an example on Xamarin.Forms of the callback implementation that replaces the SDK dialog with a custom one:

bool OnReleaseAvailable(ReleaseDetails releaseDetails)
{
    // Look at releaseDetails public properties to get version information, release notes text or release notes URL
    string versionName = releaseDetails.ShortVersion;
    string versionCodeOrBuildNumber = releaseDetails.Version;
    string releaseNotes = releaseDetails.ReleaseNotes;
    Uri releaseNotesUrl = releaseDetails.ReleaseNotesUrl;

    // custom dialog
    var title = "Version " + versionName + " available!";
    Task answer;

    // On mandatory update, user can't postpone
    if (releaseDetails.MandatoryUpdate)
    {
        answer = Current.MainPage.DisplayAlert(title, releaseNotes, "Download and Install");
    }
    else
    {
        answer = Current.MainPage.DisplayAlert(title, releaseNotes, "Download and Install", "Maybe tomorrow...");
    }
    answer.ContinueWith((task) =>
    {
        // If mandatory or if answer was positive
        if (releaseDetails.MandatoryUpdate || (task as Task<bool>).Result)
        {
            // Notify SDK that user selected update
            Distribute.NotifyUpdateAction(UpdateAction.Update);
        }
        else
        {
            // Notify SDK that user selected postpone (for 1 day)
            // This method call is ignored by the SDK if the update is mandatory
            Distribute.NotifyUpdateAction(UpdateAction.Postpone);
        }
    });

    // Return true if you're using your own dialog, false otherwise
    return true;
}

Implementation notes for Xamarin.Android:

As shown in the example, you must either call Distribute.NotifyUpdateAction(UpdateAction.UPDATE); or Distribute.NotifyUpdateAction(UpdateAction.POSTPONE); if your callback returns true.

If you don't call NotifyUpdateAction, the callback will repeat on every activity change.

The callback can be called again with the same release if the activity changes before the user action is notified to the SDK.

This behavior is needed to cover the following scenarios:

  • Your application is sent to the background (like pressing HOME) then resumed in a different activity.
  • Your activity is covered by another one without leaving the application (like clicking on some notifications).
  • Other similar scenarios.

In that case, the activity hosting the dialog might be replaced without user interaction. So the SDK calls the listener again so that you can restore the custom dialog.

3. Execute code if no updates are found

In cases when the SDK checks for updates and doesn't find any updates available newer than the one currently used, a NoReleaseAvailable callback is invoked. This allows you to execute custom code in such scenarios. You need to register the callback before calling AppCenter.Start as shown in the following example:

// In this example OnNoReleaseAvailable is a method name in same class
Distribute.NoReleaseAvailable = OnNoReleaseAvailable;
AppCenter.Start(...);
void OnNoReleaseAvailable()
{
    AppCenterLog.Info(LogTag, "No release available callback invoked.");
}

Enable or disable App Center Distribute at runtime

You can enable and disable App Center Distribute at runtime. If you disable it, the SDK won't provide any in-app update functionality but you can still use Distribute service in App Center portal.

Distribute.SetEnabledAsync(false);

To enable App Center Distribute again, use the same API but pass true as a parameter.

Distribute.SetEnabledAsync(true);

You don't need to await this call to make other API calls (such as IsEnabledAsync) consistent.

The state is persisted in the device's storage across application launches.

Note

This method must only be used after Distribute has been started.

Check if App Center Distribute is enabled

You can also check if App Center Distribute is enabled or not:

bool enabled = await Distribute.IsEnabledAsync();

Note

This method must only be used after Distribute has been started, it will always return false before start.

Perform clean up right before the app closes for update (iOS only)

Register callback as shown in the following example:

// In this example, OnWillExitApp is a method name in same class
Distribute.WillExitApp = OnWillExitApp;
void OnWillExitApp()
{
    // Perform clean up here
}

With that, OnWillExitApp() will be invoked when Distribute is about to close.

How do in-app updates work?

Note

For in-app updates to work, an app build should be downloaded from the link. It won't work if installed from an IDE or manually.

The in-app updates feature works as follows:

  1. This feature only works with RELEASE builds (by default) that are distributed using App Center Distribute service. It won't work if the iOS Guided Access feature is turned on.

  2. Once you integrate the SDK, build release version of your app and upload to App Center, users in that distribution group will be notified for the new release via an email.

  3. When each user opens the link in their email, the application will be installed on their device. It's important that they use the email link to install - we don't support side-loading. When an application is downloaded from the link, the SDK saves important information from cookies to check for updates later, otherwise the SDK doesn’t have that key information.

  4. If the application sets the track to private, a browser will open to authenticate the user and enable in-app updates. The browser won't open again as long as the authentication information remains valid even when switching back to the public track and back to private again later. If the browser authentication is successful, the user is redirected back to the application automatically. If the track is public (which is the default), the next step happens directly.

    • On iOS 9 and 10, an instance of SFSafariViewController will open within the app to authenticate the user. It will close itself automatically after the authentication succeeded.
    • On iOS 11, the user experience is similar to iOS 10 but iOS 11 will ask the user for their permission to access login information. This is a system level dialog and it can't be customized. If the user cancels the dialog, they can continue to use the version they're testing, but they won't get in-app-updates. They'll be asked to access login information again when they launch the app the next time.
  5. A new release of the app shows the in-app update dialog asking users to update your application if it's:

    • iOS:

      • a higher value of CFBundleShortVersionString or
      • an equal value of CFBundleShortVersionString but a higher value of CFBundleVersion.
      • the versions are the same but the build unique identifier is different.
    • Android:

      • a higher value of versionCode or
      • an equal value of versionCode but a different value of versionName.

Tip

If you upload the same apk/ipa a second time, the dialog will NOT appear as the binaries are identical. On iOS, if you upload a new build with the same version properties, it will show the update dialog. The reason for this is that it's a different binary. On Android, binaries are considered the same if both version properties are the same.

How do I test in-app updates?

You need to upload release builds (that use the Distribute module of the App Center SDK) to the App Center Portal to test in-app updates, increasing version numbers every time.

  1. Create your app in the App Center Portal if you haven't already.
  2. Create a new distribution group and name it, so you can recognize it's meant for testing the in-app update feature.
  3. Add yourself (or all people who you want to include on your test of the in-app update feature). Use a new or throw-away email address for this, that wasn't used for that app on App Center. This ensures that your experience is close to the experience of your real testers.
  4. Create a new build of your app that includes App Center Distribute and contains the setup logic as described below. If the group is private, don't forget to set the private in-app update track before start using the UpdateTrack property.
  5. Click on the Distribute new release button in the portal and upload your build of the app.
  6. Once the upload has finished, click Next and select the Distribution group that you created as the Destination of that app distribution.
  7. Review the Distribution and distribute the build to your in-app testing group.
  8. People in that group will receive an invite to be testers of the app. Once they accept the invite, they can download the app from the App Center Portal from their mobile device. Once they have in-app updates installed, you're ready to test in-app updates.
  9. Bump the version of your app (CFBundleShortVersionString or CFBundleVersion for iOS, versionCode for Android)
  10. Build the release version of your app and upload a new build of your app like you did in the previous step and distribute this to the Distribution Group you created earlier. Members of the Distribution Group will be prompted for a new version the next time the app starts.

Tip

Have a look at the information on how to utilize App Center Distribute for more detailed information about Distribution Groups etc. While it's possible to use App Center Distribute to distribute a new version of your app without adding any code, adding App Center Distribute to your app's code will result in a more seamless experience for your testers and users as they get the in-app update experience.

Disable automatic forwarding of application delegate's methods to App Center services

App Center uses swizzling to automatically forward your application delegate's methods to App Center services to improve SDK integration. There's a possibility of conflicts with other third-party libraries or the application delegate itself. In this case, you might want to disable the App Center application delegate forwarding for all App Center services by following the steps below:

  1. Open the project's Info.plist file.
  2. Add AppCenterAppDelegateForwarderEnabled key and set the value to 0. This disables application delegate forwarding for all App Center services.
  3. Add OpenUrl callback in your AppDelegate.cs file.
public override bool OpenUrl(UIApplication application, NSUrl url, string sourceApplication, NSObject annotation)
{
    Distribute.OpenUrl(url);
    return true;
}