Interactive Widgets

Android and iOS (starting with iOS 17) allow widgets to have interactive Elements like Buttons. Using home_widget you can register Dart Callbacks that get invoked from the Native Widgets so you only have to write that logic once.

Flutter Setup

1. Write a static function that takes a Uri as an argument. This will get called when a user clicks on the View

   @pragma("vm:entry-point")
   FutureOr<void> backgroundCallback(Uri? data) async {
     // do something with data
     ...
   }
   

   @pragma('vm:entry-point') must be placed above the callback function to avoid tree shaking in release mode.

2. Register the callback function by calling

   HomeWidget.registerInteractivityCallback(backgroundCallback);
   

iOS Setup

1. Adjust your Podfile to add home_widget as a dependency to your WidgetExtension

   target 'YourWidgetExtension' do
      use_frameworks!
      use_modular_headers!
   
      pod 'home_widget', :path => '.symlinks/plugins/home_widget/ios'
   end
   

2. To be able to use plugins with the Background Callback add this to your AppDelegate's application function

   if #available(iOS 17, *) {
    HomeWidgetBackgroundWorker.setPluginRegistrantCallback { registry in
        GeneratedPluginRegistrant.register(with: registry)
    }
   }
   

3. Create a custom AppIntent in your App Target (Runner) and make sure to select both your App and your WidgetExtension in the Target Membership panel

   

   In this Intent you should import home_widget and call HomeWidgetBackgroundWorker.run(url: url, appGroup: appGroup!) in the perform method. url and appGroup can be either hardcoded or set as parameters from the Widget

   import AppIntents
   import Flutter
   import Foundation
   import home_widget
   
   @available(iOS 16, *)
   public struct BackgroundIntent: AppIntent {
      static public var title: LocalizedStringResource = "HomeWidget Background Intent"
   
      @Parameter(title: "Widget URI")
      var url: URL?
   
      @Parameter(title: "AppGroup")
      var appGroup: String?
   
      public init() {}
   
      public init(url: URL?, appGroup: String?) {
         self.url = url
         self.appGroup = appGroup
      }
   
      public func perform() async throws -> some IntentResult {
         await HomeWidgetBackgroundWorker.run(url: url, appGroup: appGroup!)
   
         return .result()
      }
   }
   

4. Add a Button to your Widget. This Button might be encapsulated by a Version check. Pass in an instance of the AppIntent created in the previous step

   Button(
      intent: BackgroundIntent(
        url: URL(string: "homeWidgetExample://titleClicked"), appGroup: widgetGroupId)
    ) {
      Text(entry.title).bold().font( /*@START_MENU_TOKEN@*/.title /*@END_MENU_TOKEN@*/)
    }.buttonStyle(.plain)
   

5. With the current setup the Widget is now Interactive as long as the App is still in the background. If you want to have the Widget be able to wake the App up you need to add the following to your AppIntent file

   @available(iOS 16, *)
   @available(iOSApplicationExtension, unavailable)
   extension BackgroundIntent: ForegroundContinuableIntent {}
   

   This code tells the system to always perform the Intent in the App and not in a process attached to the Widget. Note however that this will start your Flutter App using the normal main entrypoint meaning your full app might be run in the background. To counter this you should add checks in the very first Widget you build inside runApp to only perform necessary calls/setups while the App is launched in the background

Android Setup

1. Add the necessary Receiver and Service to your AndroidManifest.xml file

   <receiver android:name="es.antonborri.home_widget.HomeWidgetBackgroundReceiver"  android:exported="true">
       <intent-filter>
           <action android:name="es.antonborri.home_widget.action.BACKGROUND" />
       </intent-filter>
   </receiver>
   <service android:name="es.antonborri.home_widget.HomeWidgetBackgroundService"
       android:permission="android.permission.BIND_JOB_SERVICE" android:exported="true"/>
   

2. Create a custom Action

   class InteractiveAction : ActionCallback {
        override suspend fun onAction(context: Context, glanceId: GlanceId, parameters: ActionParameters) {
         val backgroundIntent = HomeWidgetBackgroundIntent.getBroadcast(context, Uri.parse("homeWidgetExample://titleClicked"))
         backgroundIntent.send()
       }
   }
   

3. Add the Action as a modifier to a view

   Text(
        title,
        style = TextStyle(fontSize = 36.sp, fontWeight = FontWeight.Bold),
        modifier = GlanceModifier.clickable(onClick = actionRunCallback<InteractiveAction>()),
   )
   

Example Blog Article

A more in depth guide on how to build Interactive Widgets can be found here