push_notifications_example

Push notification actions (the inline Accept / Decline / Reply buttons on a notification) are not readily available out of the box in Flutter or in the firebase_messaging plugin. This demo shows one way to add them by going native on each side and routing the user's response back to Dart through a single MethodChannel.

Accompanying the blog post: [TODO: blog link].

Notes

Flow

Notifications are intercepted on the native side, the user's tap or action is stashed, and the payload is then exposed to Flutter through a MethodChannel. The flutter_local_notifications package could replace parts of this on Android to render the notifications with action buttons, on iOS to register the notification categories. That variation will live in a separate branch.

Android

• FCM messages must be sent data only. notification key payloads are intercepted by firebase_messaging itself and rendered before our code runs.
• category is not officially supported on Android. Workaround: include it as a data field and intercept the message to render a local notification with the desired action buttons.
• Notification actions are not officially supported by Firebase Messaging.
• Background work for an action (e.g. Accept) can run via the Flutter onBackgroundMessage handler.

iOS

• Upload an APNs Auth Key (.p8) in the Firebase Console under Cloud Messaging.
• Notification categories are supported by firebase_messaging, but must be registered manually. Actions are not supported.
• onBackgroundMessage is not supported on iOS due to platform limits.
• Background work for an action must be done native (Swift), since Dart isn't available from a background notification response on iOS.

Sample payload

Send to the FCM HTTP v1 endpoint (https://fcm.googleapis.com/v1/projects/<PROJECT_ID>/messages:send). Replace <FCM_TOKEN> with the device token printed by the app in debug builds. The same payload works for both platforms, FCM ignores the apns block on Android and the android block on iOS.

{
  "message": {
    "token": "<FCM_TOKEN>",
    "apns": {
      "payload": {
        "aps": {
          "alert": {
            "title": "Hello from postman"
          },
          "sound": "default",
          "category": "ACTIONS_CATEGORY"
        }
      }
    },
    "android": {
      "notification": {
        "channel_id": "high_importance_channel"
      },
      "data": {
        "category": "ACTIONS_CATEGORY",
        "title": "Hello from postman",
        "body": "Notification body"
      }
    }
  }
}

Authors

• Author: Zvonimir Babić
• Mentor: Ivan Celija