Push notifications with back stack (Pending Intents, Kotlin)

Question

I'm facing a problem with passing the launch URL from one activity to another, without creating a new Intent for my MainActivity.

I have a webview, which is work with OneSignal push notifications. I wanted to modify the grouping notifications content.

If there's a way to get the result I want (modifying notifications group layout for OneSignal) That would be awesome. I'll simply use the One Signal default action and that would be the best solution for me.

If I have to implement it on that way: https://developer.android.com/training/notify-user/group

The problem is, when I start a new child activity of the MainActivity, I don't use the "StartActivity / StartActivityForResults" functions. This is the extension of OSRemoteNotificationReceivedHandler (OneSignal class) It's outside of my MainActivity class.

    class NotificationServiceExtension : OSRemoteNotificationReceivedHandler {
    @RequiresApi(Build.VERSION_CODES.N)
    override fun remoteNotificationReceived(
        context: Context,
        notificationReceivedEvent: OSNotificationReceivedEvent
    ) {
        val notification = notificationReceivedEvent.notification
        val bigText = Html.fromHtml(notification.body, FROM_HTML_MODE_LEGACY).toString()
        var smallText = Html.fromHtml(notification.additionalData["cleantitle"] as String, FROM_HTML_MODE_LEGACY).toString()
        val summaryStatistics = Html.fromHtml(notification.additionalData["setSummaryText"] as String, FROM_HTML_MODE_LEGACY).toString()

        if (smallText == "test") {
            smallText = Html.fromHtml(notification.additionalData["smalltitle"] as String, FROM_HTML_MODE_LEGACY).toString()
        }
        else{
            val name = Html.fromHtml(notification.additionalData["text"] as String, FROM_HTML_MODE_LEGACY).toString()
            smallText += " from $name"
        }

        val smallContent = RemoteViews("com.webviewapp.mywebviewapp", R.layout.small_layout_notification)
        val sum = RemoteViews("com.webviewapp.mywebviewapp", R.layout.summary_layout_notification)
        val bigContent = RemoteViews("com.webviewapp.mywebviewapp", R.layout.large_notification_layout)

        bigContent.setTextViewText(R.id.notification_title, smallText)
        bigContent.setTextViewText(R.id.notification_content, bigText)
        smallContent.setTextViewText(R.id.notification_title, smallText)
        sum.setTextViewText(R.id.notification_title, summaryStatistics)
        notificationReceivedEvent.complete(null)


        var bp: Bitmap? = null
        try {
            bp =Picasso.get().load(notification.largeIcon).get()
            smallContent.setImageViewBitmap(R.id.noti_pic, bp)
            bigContent.setImageViewBitmap(R.id.noti_pic, bp)

        }
        catch(e:Exception){
            print(e)
        }

        try {
            val fid = notification.additionalData["fid"] as String
            notificationId = fid.toInt()

        }
        catch(e:java.lang.Exception){
            notificationId += Date().time.toInt()
        }

        val notificationOpenActivity = Intent(context.applicationContext, MainActivity::class.java)
            .putExtra("launchURL", notification.additionalData["pushURL"] as String)
            .setFlags(Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK)


        val resultPendingIntent: PendingIntent? = TaskStackBuilder.create(context.applicationContext).run {
            // Add the intent, which inflates the back stack
            addNextIntentWithParentStack(notificationOpenActivity)

            // Get the PendingIntent containing the entire back stack
            getPendingIntent(0,
                PendingIntent.FLAG_UPDATE_CURRENT)
        }


        val receivedNotification = NotificationCompat.Builder(context.applicationContext, NOTIFICATION_GROUP)
            .setSmallIcon(R.drawable.myIcon)
            .setColor(ContextCompat.getColor(context.applicationContext,R.color.blue_primary))
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            .setStyle(NotificationCompat.DecoratedCustomViewStyle()) // to expand button
            .setAutoCancel(true)
            .setVibrate(longArrayOf(500, 500, 500))
            .setCustomBigContentView(bigContent)
            .setCustomContentView(smallContent)
            .setCustomHeadsUpContentView(sum)
            .setChannelId(NOTIFICATION_CHANNEL)
            .setGroup(NOTIFICATION_GROUP)
            .setGroupSummary(false)
            .setContentIntent(resultPendingIntent)
            .build()


        val summary = NotificationCompat.Builder(context.applicationContext, NOTIFICATION_GROUP)
            .setSmallIcon(R.drawable.myIcon)
            .setColor(ContextCompat.getColor(context.applicationContext,R.color.blue_primary))
            //.setContentTitle(summaryStatistics.toString())
            .setContentTitle(summaryStatistics)
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            .setStyle(NotificationCompat.InboxStyle()
                .setBigContentTitle(summaryStatistics)
                .addLine(summaryStatistics)
                .setSummaryText(summaryStatistics))
            .setAutoCancel(true)
            .setChannelId(NOTIFICATION_CHANNEL)
            .setGroup(NOTIFICATION_GROUP)
            .setGroupSummary(true)
            .build()

        NotificationManagerCompat.from(context.applicationContext).apply {
            notify(notificationId, receivedNotification)
            notify(SUMMARY_ID, summary)
        }


    }
}

And the notifications work good as I want. The problem is, How do I pass from the child activity the extra parameter to it's parent if I didn't create that child from the parent? I simply want to load it's URL into my webview, but also keep the back stack. Also, how can I make sure I don't create multiple MainActivity if I won't use that child?

Thanks in advance.

Answer 1

Notification Back Stack

Android's documentation page "Start an Activity from a Notification" covers the back stack use case under the "Regular activity" suggestion.

Regular activity

This is an activity that exists as a part of your app's normal UX flow. So when the user arrives in the activity from the notification, the new task should include a complete back stack, allowing them to press Back and navigate up the app hierarchy.

I see you are using the addNextIntentWithParentStack method on TaskStackBuilder already in your code so looks like you may have already followed that page. However there is one thing wrong with Google's docs here, the requestCode sent to getPendingIntent should be a unique value for your app. Example:

   getPendingIntent(
      1234, // NOTE: Change this to a unique requestCode for your app
      PendingIntent.FLAG_UPDATE_CURRENT
   )

I have filed an docs issue with Google on this.

Lastly, since I didn't see this in your question make sure you have correctly added android:parentActivityName to your Activity in your AndroidManifest.xml per Android's "Define your app's Activity hierarchy"

OneSignal Details

Notification Tracking

Note that calling notificationReceivedEvent.complete(null) means OneSignal won't know anything about your notification you're displaying with NotificationManagerCompat. This changes a few things:

• Click counts won't be sent to OneSignal
• Notification won't be restored. (notifications are automatically cleaned when the app is "force stopped", device is rebooted, or app is updated)

Notification Groups

OneSignal can already do the grouping and summary you have in your code. Just set the "Group Key" on the dashboard, or android_group if you are sending the notification with the REST API.

Back stack

OneSignal doesn't allow you to control the back stack, it simply just always resumes that app and leaves the back stack un-effected. However you can disable this default behavior with com.onesignal.NotificationOpened.DEFAULT in your AndroidManifest.xml and use your own startActivity from the OneSignal.setNotificationOpenedHandler.