backToForeground() does not work when app is closed on Android

[jfaltis]

First of all: This is a very nice library! I am using callkeep to display an incoming call notification when a message is received via firebase_messaging in onBackgroundMessage. When the user answers the incoming call I call backToForeground() and endCall() to just open the app when answering the call. This works pretty good when the app is running and in the background.

But when the app is closed and a message is received it shows the incoming call notification but when you click on answer, it doesn't launch the app.

I think this is a critical feature for such use case since it can't be guaranteed that the app is alive. I don't know how easy it is to extend backToForeground() so it handles this case properly or if this is even possible at all.

I have yet to test the behavior on iOS if it launches the app by default because backToForeground is not implemented for iOS according to the source code of callkeep.

If you know an alternative solution, please let me know.

[ghenry]

I've read your issue and I have not tried it that way. I am answering
the call and then answering the SIP INVITE in dart-sip-ua and staying
in the native dialler screen and using all the callbacks for hold/dtmf
etc.

Once a successful call is ended I am about to use backtoforeground,
but I haven't tested that yet.

If you end the call, what are you doing about the native dialler call
logs? Isn't the call recorded there? What is the architecture of your
app like? SIP?

Regarding iOS, I understand true background messages do not work
with FCM, just onLaunch and onResume, so I am using what apple say to
use for VoIP:

firebase/flutterfire#116 (comment)
https://github.com/masashi-sutou/flutter_ios_voip_kit

I may move to this though for a custom inbound call screen or copy it to this project:

https://github.com/doneservices/flutter_callkeep/blob/01e683d16be6d6675cf678d85be683718382a96a/lib/flutter_callkeep.dart#L248

doneservices/flutter_callkeep#16

[ghenry]

It looks like it’s not implemented

https://github.com/flutter-webrtc/callkeep/search?q=foreground

It is in another project https://github.com/doneservices/flutter_callkeep/blob/b15c0caffacdf4aa2cc3f118f66a6980cb11cb24/android/src/main/kotlin/co/doneservices/callkeep/CallKeep.kt#L381

[ghenry]

Actually, callKeep.backToForeground(); is working for me. It is there

callkeep/android/src/main/java/io/wazo/callkeep/CallKeepModule.java

Line 546 in 002ea8e

public void backToForeground(@NonNull MethodChannel.Result result) {

[jfaltis]

If you end the call, what are you doing about the native dialler call
logs? Isn't the call recorded there? What is the architecture of your
app like? SIP?

I planned to use it only for the incoming call notification and I didn't thought alot about call logs. Can you prevent it from being written to the call logs? If it's not possible then I think it is not that dramatic. I want to use Agora for Video Calling with custom UI and therefore I just need the incoming call notification to open the app. This library is the most promising thing I found which could work on iOS and Android with Flutter.

Regarding iOS, I understand true background messages do not work
with FCM, just onLaunch and onResume, so I am using what apple say to

I know that onBackgroundMessage is not supported by firebase_messaging yet but there is a PR (firebase/flutterfire#2016) and a Google dev commented "Hold on to your hats... New dev release coming soon." so I think this is going to be merged soon. I also read somewhere that CallKit which is used for iOS always opens the app. So if onBackgroundMessage is working reliably on iOS this might be a good solution if Android behaved the same.

use for VoIP:
FirebaseExtended/flutterfire#116 (comment)
https://github.com/masashi-sutou/flutter_ios_voip_kit

This also looks interesting if the PR with onBackgroundMessage won't work reliably on iOS.

I may move to this though for a custom inbound call screen or copy it to this project:

https://github.com/doneservices/flutter_callkeep/blob/01e683d16be6d6675cf678d85be683718382a96a/lib/flutter_callkeep.dart#L248

doneservices/flutter_callkeep#16

That also looks interesting

Actually, callKeep.backToForeground(); is working for me. It is there

callkeep/android/src/main/java/io/wazo/callkeep/CallKeepModule.java

Line 546 in 002ea8e

public void backToForeground(@NonNull MethodChannel.Result result) {

It is working for you when the app is killed? It is working for me only when the app is in background but not when it was killed. What Android version?

[ghenry]

Thanks for all your replies. Great info. Ah, not tested a killed app.

[jfaltis]

I wanted to test if the implementation of backToForeground() of the other library (https://github.com/doneservices/flutter_callkeep) can open the app when it was killed but I could not get it running in the background, only foreground. It's the same problem another person was facing: doneservices/flutter_callkeep#19

[ghenry]

I read up on the flag used to do this on the android native side, and the app needs to be running as it's moved up the activity stack. Read the source and have a Google to confirm yourself. That's my understanding anyway.

[jfaltis]

I read up on the flag used to do this on the android native side, and the app needs to be running as it's moved up the activity stack. Read the source and have a Google to confirm yourself. That's my understanding anyway.

That's what I picked up too but I made an interesting observation: When I kill the app after the incoming call notification is shown and then click on answer it works despite when backToForeground() is called when the app is closed. This seems contradicting to me.

I am also initializing CallKeep and setting the CallKeepPerformAnswerCallAction "listener" when receciving a notification. I tried initializing and setting the listener with a static instance when the app is started but that's not working. I guess because onBackgroundMessage is running as it's own service.

[aponski]

Hi @jfaltis it looks like we have the same use case :). I also want to use callkeep plugin to inform user about incoming call and then redirect to app with webrtc call. I also tried the other flutter_callkeep plugin with the same error in background mode as described here.

One question for you, how did you make callkeep plugin to work when app is terminated? Other plugins that used (flutter_local_notifications, flutter_ringtone_player) are working ok in background mode when app is terminated, but callkeep is not, nothing is shown. Any suggestions?

It would be nice if you could share your implementation of backgroundMessageHandler

[jfaltis]

Hi @aponski, I am doing all the initialization of callkeep in the onBackgroundMessage because doing it somewhere else did not properly work for me.

static Future<dynamic> onBackgroundMessage(
    Map<String, dynamic> message,
  ) async {
      final FlutterCallkeep _callKeep = FlutterCallkeep();
      _callKeep.setup(<String, dynamic>{
        'ios': {
          'appName': 'CallKeepDemo',
        },
        'android': {
          'alertTitle': 'Permissions required',
          'alertDescription':
              'This application needs to access your phone accounts',
          'cancelButton': 'Cancel',
          'okButton': 'ok',
        },
      });
      final String callUUID = Uuid().v4();
      _callKeep.on(CallKeepPerformAnswerCallAction(),
          (CallKeepPerformAnswerCallAction event) {
        _callKeep.backToForeground();
        _callKeep.endCall(event.callUUID);
      });
      _callKeep.displayIncomingCall(callUUID, "Caller Name");
  }

Maybe you haven't registered the Plugin properly?

My Application.kt

package your.package.name

import io.flutter.app.FlutterApplication
import io.flutter.plugin.common.PluginRegistry
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback
import io.flutter.plugins.GeneratedPluginRegistrant
import io.flutter.plugins.firebasemessaging.FlutterFirebaseMessagingService
import com.github.cloudwebrtc.flutter_callkeep.FlutterCallkeepPlugin

class Application : FlutterApplication(), PluginRegistrantCallback {
  override fun onCreate() {
    super.onCreate()
    FlutterFirebaseMessagingService.setPluginRegistrant(this)
  }

  override fun registerWith(registry: PluginRegistry?) {
    io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin.registerWith(registry?.registrarFor("io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin"));
    FlutterCallkeepPlugin.registerWith(registry?.registrarFor("com.github.cloudwebrtc.flutter_callkeep"));
  }
}

[aponski]

@jfaltis thanks a lot, initialization in background message handler did the job, it's working. Now I guess we have to figure out hot to make backToForeground() work when app is terminated. Any ideas?

[jfaltis]

@aponski I am happy to help you :) Yes I guess that is the only thing we have to figure out to make it work reliably on Android. But I don't know if this will also work reliably on iOS with the onBackgroundMessage PR for iOS (firebase/flutterfire#2016). I currently don't have an iOS Device nor an Apple Developer Account to test this. Could you maybe test that?

[aponski]

@jfaltis sure, I will test it on iOS and let you know

[aponski]

@jfaltis Here is a nice summary of what’s working regarding notifications on Android and iOS: link. On iOS I think the only way is to use voip notifications (Apple PushKit) with an additional flutter plugin flutter_voip_push_notification. I will try it but currently my main concern is to make it fully work on Android first.

[ghenry]

This is also my understanding and my plan too. Android first, but I have a feeling the background message is isolating some of my code which I am investigating.

…