Hey there! Let's tackle your two Xamarin.Android notification control requirements step by step:

Absolutely, this is achievable—but it depends on securing the right permissions and handling Android's notification system nuances across different API levels. Here's how to make it work:

First, Secure the Required Permission #

You'll need the ACCESS_NOTIFICATION_POLICY permission, a sensitive system-level permission that can't be granted via standard runtime requests. Add it to your AndroidManifest.xml first:

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

Then, prompt users to enable it through the system settings (this is mandatory):

var notificationManager = (NotificationManager)GetSystemService(NotificationService);
if (!notificationManager.IsNotificationPolicyAccessGranted)
{
    var intent = new Intent(Android.Provider.Settings.ActionNotificationPolicyAccessSettings);
    StartActivity(intent);
}

Toggle Notifications for Target Apps #

Android handles notifications differently pre-Oreo (API 26) and post-Oreo. Use this cross-version method to disable/enable notifications for apps like Facebook or Instagram:

public void ToggleAppNotifications(string packageName, bool disable)
{
    var notificationManager = (NotificationManager)GetSystemService(NotificationService);
    
    if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
    {
        // For Android 8.0+, modify all notification channels for the app
        var channels = notificationManager.GetNotificationChannelsForPackage(packageName);
        foreach (var channel in channels)
        {
            channel.Importance = disable ? NotificationImportance.None : NotificationImportance.Default;
            notificationManager.CreateNotificationChannel(channel);
        }
    }
    else
    {
        // Pre-Oreo, block/unblock all notifications for the package
        var policy = disable ? NotificationPackagePolicy.Block : NotificationPackagePolicy.Allow;
        notificationManager.SetPackageNamePolicy(packageName, policy);
    }
}

Schedule Time-Based Toggles #

To trigger disable/enable actions at your desired times, use WorkManager (recommended for background tasks that respect battery optimization rules):

• Create a OneTimeWorkRequest to run the disable logic at your start time, and another to re-enable notifications at the end time.
• For recurring schedules, use PeriodicWorkRequest to repeat the toggle on your specified interval.

Since you already have the installed apps list, combine it with the toggle logic above and schedule the task to run automatically:

Step 1: Iterate Through Installed Apps #

Loop through your app list and apply the toggle method to each third-party app (skip system apps if needed):

public void ToggleAllAppNotifications(bool disable)
{
    var packageManager = PackageManager;
    var installedApps = packageManager.GetInstalledApplications(PackageInfoFlags.MetaData);
    
    foreach (var app in installedApps)
    {
        // Skip system apps to target only third-party apps
        if (!app.Flags.HasFlag(ApplicationInfoFlags.System))
        {
            ToggleAppNotifications(app.PackageName, disable);
        }
    }
}

Step 2: Schedule the Recurring Task #

First, define a Worker class to handle the background logic:

public class NotificationToggleWorker : Worker
{
    public NotificationToggleWorker(Context context, WorkerParameters parameters) : base(context, parameters) { }

    public override Result DoWork()
    {
        // Add your logic to check if it's time to disable/enable notifications
        bool shouldDisable = /* Your time-based condition here */;
        // Use a helper class or pass context to access the toggle method
        var notificationHelper = new NotificationHelper(Context);
        notificationHelper.ToggleAllAppNotifications(shouldDisable);
        
        return Result.Success;
    }
}

Then schedule the periodic work (e.g., every 2 hours):

var periodicWork = PeriodicWorkRequestBuilder<NotificationToggleWorker>(TimeSpan.FromHours(2))
    .AddTag("notification_toggle_schedule")
    .Build();

WorkManager.Instance.Enqueue(periodicWork);

Key Notes #

• Test across multiple Android versions—notification behavior shifts significantly between API levels.
• Users can override your settings manually via system notification settings, so it's wise to inform them about this feature upfront.
• WorkManager is preferred over AlarmManager because it adapts to Android's doze mode and battery optimization policies.

内容的提问来源于stack exchange，提问作者Aya