AppIcon Badge with .NET MAUI

Winter is coming!

This article is a continuation of a series of potential Essentials APIs, that can be added to .NET MAUI later. It is devoted to the AppIcon badge. If your app sends notifications or you want the user to pay attention to the app, this API is what you need.

As usual, starting from creating the interface:

public interface INotificationCounter
{
	void SetNotificationCount(int count);
}

public static class NotificationCounter
{
	static INotificationCounter? defaultImplementation;

	public static void SetNotificationCount(int count)
	{
		Default.SetNotificationCount(count);
	}

	public static INotificationCounter Default =>
		defaultImplementation ??= new NotificationCounterImplementation();

	internal static void SetDefault(INotificationCounter? implementation) =>
		defaultImplementation = implementation;
}

We need only 1 method that sets badge count. If the count is 0 or less, the badge is removed.

Android

In Android, icons are displayed in the launcher, and there are a lot of different launchers. Each of them requires its own permissions and implementations. I recommend installing the next NuGet package:

<ItemGroup Condition="'$(TargetFramework)' == 'net7.0-android'">
  <PackageReference Include="Xamarin.Android.ShortcutBadger" Version="1.2.0" />
</ItemGroup>

Add the next permissions to AndroidManifest.xml:

<uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>

<uses-permission android:name="com.sonymobile.home.permission.PROVIDER_INSERT_BADGE" />
<uses-permission android:name="com.majeur.launcher.permission.UPDATE_BADGE" />
<uses-permission android:name="com.huawei.android.launcher.permission.CHANGE_BADGE" />
<uses-permission android:name="com.huawei.android.launcher.permission.READ_SETTINGS" />
<uses-permission android:name="com.huawei.android.launcher.permission.WRITE_SETTINGS" />
<uses-permission android:name="android.permission.READ_APP_BADGE" />
<uses-permission android:name="com.oppo.launcher.permission.READ_SETTINGS" />
<uses-permission android:name="com.oppo.launcher.permission.WRITE_SETTINGS" />
<uses-permission android:name="me.everything.badger.permission.BADGE_COUNT_READ" />
<uses-permission android:name="me.everything.badger.permission.BADGE_COUNT_WRITE" />

<!-- Apex -->
<uses-permission android:name="com.anddoes.launcher.permission.UPDATE_COUNT"/>

<!-- Default -->
<uses-permission android:name="com.android.launcher.permission.READ_SETTINGS"/>
<uses-permission android:name="com.android.launcher.permission.WRITE_SETTINGS"/>
<uses-permission android:name="com.android.launcher.permission.INSTALL_SHORTCUT" />
<uses-permission android:name="com.android.launcher.permission.UNINSTALL_SHORTCUT" />

<!-- HTC -->
<uses-permission android:name="com.htc.launcher.permission.READ_SETTINGS" />
<uses-permission android:name="com.htc.launcher.permission.UPDATE_SHORTCUT" /> 

<!-- Samsung -->
<uses-permission android:name="com.sec.android.provider.badge.permission.READ" />
<uses-permission android:name="com.sec.android.provider.badge.permission.WRITE" />

<!-- Sony -->
<uses-permission android:name="com.sonyericsson.home.permission.BROADCAST_BADGE" />
<uses-permission android:name="com.sonymobile.home.permission.PROVIDER_INSERT_BADGE" />

And finally, implement our interface:

public class NotificationCounterImplementation : INotificationCounter
{
	public void SetNotificationCount(int count)
	{
		ME.Leolin.Shortcutbadger.ShortcutBadger.ApplyCount(Application.Context, count);
    }
}

iOS/MacCatalyst

Apple's implementation is much simpler:

public class NotificationCounterImplementation : INotificationCounter
{
	public void SetNotificationCount(int count)
	{
		UNUserNotificationCenter.Current.RequestAuthorization(UNAuthorizationOptions.Badge, (r, e) =>
		{
		});
		UIApplication.SharedApplication.ApplicationIconBadgeNumber = count;
	}
}

You request NotificationCenter permission to update the badge. After that, you can update the Badge number.

Windows

Windows doesn't require any permissions or additional packages:

public class NotificationCounterImplementation : INotificationCounter
{
	public void SetNotificationCount(int count)
	{
		var badgeUpdater =	BadgeUpdateManager.CreateBadgeUpdaterForApplication();
		if (count <= 0)
		{
			badgeUpdater.Clear();
		}
		else
		{
			var badgeXml = BadgeUpdateManager.GetTemplateContent(BadgeTemplateType.BadgeNumber);

			var badgeElement = badgeXml.SelectSingleNode("/badge") as XmlElement;
			badgeElement?.SetAttribute("value", count.ToString());

			var badge = new BadgeNotification(badgeXml);
			badgeUpdater.Update(badge);
		}
	}
}

Tizen

And last, but not least. Tizen has its own control to work with badges - BadgeControl.

But first, you need to set permission in tizen-manifest.xml:

<privilege>http://tizen.org/privilege/notification</privilege>

Then implement our interface:

public class NotificationCounterImplementation : INotificationCounter
{
	public void SetNotificationCount(int count)
	{
		var appId = Application.Current.ApplicationInfo.ApplicationId;
		if (count is 0)
		{
			BadgeControl.Remove(appId);
			return;
		}
		
		var badge = BadgeControl.Find(appId);
		if (badge is null)
		{
			badge = new Badge(appId, count);
			BadgeControl.Add(badge);
		}
		else
		{
			badge.Count = count;
			BadgeControl.Update(badge);
		}
	}
}

Tizen doesn't allow adding multiple badges to the same application, so you also need to check if the badge already exists and update it.

Result

Now we can call our API and see the result:

var count = 1;
NotificationCounter.Default.SetNotificationCount(count);

The final code can be found on GitHub.

Happy coding!