Announcement Scheduler

A Flutter package for scheduling announcements with support for one-time, recurring notifications and text-to-speech.

Features

  • 📅 Flexible Scheduling: Schedule announcements for specific times or recurring patterns
  • 🔄 Recurring Patterns: Daily, weekdays, weekends, or custom day selections
  • 🔊 Text-to-Speech: Built-in TTS support with configurable voice settings
  • 📱 Single-Platform: Currently only Android support.
  • ⚙️ Configurable: Extensive configuration options for notifications and TTS
  • 🛡️ Validation: Built-in validation to prevent excessive notifications
  • 🌍 Timezone Support: Timezone-aware scheduling with optional forced timezones

Installation

Add this package to your pubspec.yaml:

dependencies:
  announcement_scheduler: ^1.1.0

Then run:

flutter pub get

Quick Start

The recommended way to use this package is by creating a dedicated service to manage initialization and scheduling. This ensures proper handling of permissions and configuration.

1. Initialize in Main

See Platform Setup below for necessary Android configuration.

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  
  try {
    // Initialize the service
    final service = await AnnouncementService.create(
      // See AnnouncementConfig below for configuration options
      config: AnnouncementConfig(   
        notificationConfig: NotificationConfig(
          channelId: 'daily_reminders',
          channelName: 'Daily Reminders',
          channelDescription: 'Daily motivational announcements',
        ),
      ),
    );

    // Schedule announcements using your service methods
    await service.scheduleWeekly(
      content: 'Time for your workout!',
      announcementTime: TimeOfDay(hour: 7, minute: 0),
      daysOfWeek: [1, 3, 5], // Monday, Wednesday, Friday
    );
    
  } catch (e) {
    print('Failed to initialize: $e');
  }

  runApp(MyApp());
}

Configuration

AnnouncementConfig

Configure the scheduler's behavior:

final config = AnnouncementConfig(
  enableTTS: true,
  ttsRate: 0.5,          // Speech rate (0.0 to 1.0)
  ttsPitch: 1.0,         // Speech pitch (0.5 to 2.0) 
  ttsVolume: 1.0,        // Speech volume (0.0 to 1.0)
  ttsLanguage: 'en-US',  // TTS language
  forceTimezone: true,
  timezoneLocation: 'UTC',  // Important to update this to device/user timezone, otherwise notifications will default to show at UTC time
  notificationConfig: NotificationConfig(
    channelId: 'announcements',
    channelName: 'Announcements',
    channelDescription: 'Scheduled announcements',
    importance: Importance.high,
    enableLights: true,
    enableVibration: true,
  ),
  validationConfig: ValidationConfig(
    maxNotificationsPerDay: 10,
    maxScheduledNotifications: 50,
    enableEdgeCaseValidation: true,
  ),
);

Recurrence Patterns

Support for various recurring patterns:

// Once off
await service.scheduleOnceOff(
  content: 'One-time reminder!',
  dateTime: DateTime.now().add(Duration(hours: 2)),
);

// Daily
await service.scheduleDaily(
  content: 'Daily reminder!',
  announcementTime: TimeOfDay(hour: 9, minute: 0),
);  

// Weekly (on specific days)
await service.scheduleWeekly(
  content: 'Weekly reminder!',
  announcementTime: TimeOfDay(hour: 10, minute: 0),
  daysOfWeek: [1, 3, 5], // Monday, Wednesday, Friday
);

### Timezone Configuration

The package supports flexible timezone configuration to ensure announcements
are delivered at the correct local time for your users:

#### Using System Timezone (Default)

By default, the package uses the device's system timezone:

```dart
final scheduler = await AnnouncementScheduler.initialize(
  config: AnnouncementConfig(
    // forceTimezone is false by default, uses system timezone
    notificationConfig: NotificationConfig(...),
  ),
);

Using a Specific Timezone

You can force a specific timezone for consistent scheduling regardless of device location:

final scheduler = await AnnouncementScheduler.initialize(
  config: AnnouncementConfig(
    forceTimezone: true,
    timezoneLocation: 'America/New_York',  // IANA timezone identifier
    notificationConfig: NotificationConfig(...),
  ),
);

Dynamic Timezone Based on User Location

For apps that serve users in different timezones, you can determine the timezone based on the user's selected location:

// Example: Get timezone from user's city selection
String getUserTimezone(String city) {
  final timezoneMap = {
    'New York': 'America/New_York',
    'Los Angeles': 'America/Los_Angeles',
    'London': 'Europe/London',
    'Tokyo': 'Asia/Tokyo',
    'Sydney': 'Australia/Sydney',
  };
  return timezoneMap[city] ?? 'America/New_York';  // Default fallback
}

// Initialize with user's timezone
final userCity = getUserSelectedCity();  // Your app's method
final scheduler = await AnnouncementScheduler.initialize(
  config: AnnouncementConfig(
    forceTimezone: true,
    timezoneLocation: getUserTimezone(userCity),
    notificationConfig: NotificationConfig(...),
  ),
);

Important Notes:

  • Use standard IANA timezone identifiers (e.g., 'America/New_York', 'Europe/ London')
  • Timezone configuration affects when announcements are delivered, not the content
  • The package handles DST (Daylight Saving Time) transitions automatically
  • For location-based apps, update the scheduler configuration when the user changes their location

Use Cases

This package is perfect for:

  • Weather Apps: Daily weather announcements
  • Fitness Apps: Workout reminders and motivation
  • Productivity Apps: Task reminders and time management
  • Meditation Apps: Daily mindfulness prompts
  • Educational Apps: Study reminders and learning cues
  • Health Apps: Medication reminders and wellness tips
  • Accessibility: Voice announcements for visually impaired users

Platform Setup

Android

Add permissions to android/app/src/main/AndroidManifest.xml:

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" /> 
    <uses-permission android:name="android.permission.SCHEDULE_EXACT_ALARM" /> 
    <uses-permission android:name="android.permission.USE_EXACT_ALARM" /> 
    <application>
      <!-- Other application content -->
      
      <!-- Required receivers for flutter_local_notifications -->
        <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationReceiver" />
        <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationBootReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED"/>
                <action android:name="android.intent.action.MY_PACKAGE_REPLACED"/>
                <action android:name="android.intent.action.QUICKBOOT_POWERON" />
                <action android:name="com.htc.intent.action.QUICKBOOT_POWERON"/>
            </intent-filter>
        </receiver>
        <receiver android:exported="false" android:name="com.dexterous.flutterlocalnotifications.ActionBroadcastReceiver" />
    </application>

Add receivers within the <application> tag:

Core Library Desugaring

To support Java 8+ time APIs on older Android versions (API < 26), enable core library desugaring in android/app/build.gradle.kts:

android {
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_11
        targetCompatibility = JavaVersion.VERSION_11
        isCoreLibraryDesugaringEnabled = true  // Add this line
    }
}

dependencies {
    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.4")  // Add this dependency
}

This is required because flutter_local_notifications uses modern Java time APIs that aren't available natively on Android versions below 8.0. Without desugaring, the app will crash on older devices.

iOS

Not supported at this time. Contributions welcome!

Managing Announcements

// Get all scheduled announcements
final announcements = await scheduler.getScheduledAnnouncements(); //

// Cancel a specific announcement (using the ID from the scheduled announcement)
if (announcements.isNotEmpty) {
  await scheduler.cancelAnnouncementById(announcements.first.id); // using the first ScheduledAnnouncement's ID, but could be any ID
}

// Cancel all announcements
await scheduler.cancelScheduledAnnouncements();

// Listen to status updates
scheduler.statusStream.listen((status) {
  print('Announcement status: ${status.displayName}');
});

// Dispose when done
await scheduler.dispose();

Error Handling

The package provides specific exception types:

try {
  await scheduler.scheduleAnnouncement(
    content: 'Test announcement',
    announcementTime: TimeOfDay(hour: 8, minute: 0),
  );
} on ValidationException catch (e) {
  print('Validation error: ${e.message}');
} on NotificationPermissionDeniedException catch (e) {
  print('Permission denied: ${e.message}');
} on NotificationSchedulingException catch (e) {
  print('Scheduling failed: ${e.message}');
} on TTSInitializationException catch (e) {
  print('TTS error: ${e.message}');
}

Contributing

Contributions are welcome! Please read the contributing guidelines before submitting pull requests.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

If you have questions or need help, please:

  1. Check the documentation
  2. Search existing issues
  3. Create a new issue if needed

Changelog

See CHANGELOG.md for a detailed list of changes.

Libraries

announcement_scheduler
A Flutter package for scheduling text-to-speech notifications.