7. Registering background listeners

To register a background listener for the Sentiance SDK, you need to:

1. Define a callback in your Dart code.

2. Register your listener in your native code (once per every platform you support)

3. Declare any 3rd party plugins that you intend to make use of within the body of the Dart callback you defined on step #1

In the guide below, we will demonstrate how to register a background event timeline listener. Please note that the process is identical for the rest of the background listeners that the Sentiance SDKs provide.

1

Define a Dart callback

Create a background.dart file under your project's lib folder with the following code:

background.dart

import 'package:sentiance_event_timeline/sentiance_event_timeline.dart';

@pragma('vm:entry-point')
Future<void> registerEventTimelineListener() async {
  WidgetsFlutterBinding.ensureInitialized();
  debugPrint("Registering a new event timeline listener.");

  SentianceEventTimeline.registerEventTimelineUpdateListener((timelineEvent) {
    // Handle new timeline events here
    debugPrint("New timeline event: ${timelineEvent.toString()}");
  });
}

2

Register listener in native code

Next, you need to make changes to your native code to ensure that your registerEventTimelineListener Dart callback can get updates from the Sentiance SDK when your app is running in the background.

if you're targeting Android

Create an Application class (if you haven't already) and add the following code inside:

MainApplication.kt

import android.app.Application
import com.sentiance.event_timeline_plugin.EventTimelinePlugin

// Don't forget to update your app's manifest:
// <application android:name=".MainApplication" ...></application>
class MainApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        
        // Initialize the Sentiance SDK first
        val initResult = CorePlugin.initialize(this)
        
        // Replace '<your_app_package_name>' with the name of your app package
        // as shown inside your project's pubspec.yaml file
        val dartLibrary = "package:<your_app_package_name>/background.dart"
        // Make sure the callback name specified here matches the name of the 
        // callback you previously defined in your Dart code 
        val dartCallbackName = "registerEventTimelineListener"
        
        EventTimelinePlugin.initializeListener(
            context = this,
            dartEntryPointLibrary = dartLibrary,
            dartEntryPointFunctionName = dartCallbackName,
            includeProvisionalEvents = true
        )
    
        // Other code
    }
}

if you're targeting iOS

3

Declare 3rd party plugins

Chances are, your app has other dependencies than just the Sentiance SDKs.

In case you needed to use a certain dependency/plugin (⚠️ including any Sentiance plugin ⚠️) inside the registerEventTimelineListener callback you previously defined, you need to let the Sentiance SDK know so that we make its usage possible for you. Without it, you will not be able to utilize other plugins inside the Dart callback.

Consider the example below:

background.dart

import 'package:sentiance_core/sentiance_core.dart';
import 'package:sentiance_event_timeline/sentiance_event_timeline.dart';
import 'package:sqflite/sqflite.dart' as sqflite;

@pragma('vm:entry-point')
Future<void> registerEventTimelineListener() async {
  WidgetsFlutterBinding.ensureInitialized();

  final sqliteDatabase = sqflite.openDatabase(...);
  final corePlugin = SentianceCore();
  final eventTimelinePlugin = SentianceEventTimeline();

  SentianceEventTimeline.registerEventTimelineUpdateListener((timelineEvent) async {
    final userId = await corePlugin.getUserId();
    eventTimelinePlugin.setTransportTags({"tag": "value"});
  });
}

The calls on line 9, 14, and 15 will fail unless you register the sqflite, core and event timeline plugins respectively. To do that, update your native code accordingly:

Android

MainApplication.kt

import android.app.Application
import com.sentiance.core_plugin.CorePlugin
import com.sentiance.event_timeline_plugin.EventTimelinePlugin
import com.tekartik.sqflite.SqflitePlugin

class MainApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        
        // Initialize the Sentiance SDK first
        val initResult = CorePlugin.initialize(this)
        
        val dartLibrary = "package:<your_app_package_name>/background.dart"
        val dartCallbackName = "registerEventTimelineListener"
        
        EventTimelinePlugin.initializeListener(
            context = this,
            dartEntryPointLibrary = dartLibrary,
            dartEntryPointFunctionName = dartCallbackName,
            includeProvisionalEvents = true
        ) { flutterEngine ->
            // flutterEngine is the environment where your Dart callback runs
            flutterEngine.plugins.apply {
                add(SqflitePlugin())
                add(CorePlugin())
                add(EventTimelinePlugin())
                // add here any other plugin that you intend to use
            }
        }
    
        // Other code
    }
}

iOS

You can also choose to register all the plugins of your app instead, if that would be more practical:

Android

MainApplication.kt

import android.app.Application
import com.sentiance.core_plugin.CorePlugin
import com.sentiance.event_timeline_plugin.EventTimelinePlugin
import io.flutter.plugins.GeneratedPluginRegistrant

class MainApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        
        // Initialize the Sentiance SDK first
        val initResult = CorePlugin.initialize(this)
        
        val dartLibrary = "package:<your_app_package_name>/background.dart"
        val dartCallbackName = "registerEventTimelineListener"
        
        EventTimelinePlugin.initializeListener(
            context = this,
            dartEntryPointLibrary = dartLibrary,
            dartEntryPointFunctionName = dartCallbackName,
            includeProvisionalEvents = true
        ) { flutterEngine ->
            // flutterEngine is the environment where your Dart callback runs
            
            // The GeneratedPluginRegistrant class is generated by the Flutter tool
            // and allows you to register all of your app's plugins with a single flutter engine
            GeneratedPluginRegistrant.registerWith(flutterEngine)
        }
    
        // Other code
    }
}

iOS

That's it. Your listener is now set up to get timeline event updates from the Sentiance SDK in the background, and can work side-by-side with other plugins that your app requires.