iOS Conference Publish from background

[Yury Grinenko]

Hi guys

I have an issue with stream publishing in conference call from background. 

When application is not running, device is locked, and incoming call arrives, CallKit offers to join the call. User accepts call. Application starts running in the background. "Under the hood" application successfully joins the room, starts playing streams in the room (user can hear all participants, so audio session is configured and works). But there is a problem with publishing. Application sends `publish` command, receives `start`, `offer`-`answer` communication takes place, but it never receives `publish_started` command. And after about 15 seconds in the call it leaves the room. Remote participants do not receive any remote stream from this device. During this time period user may open the application (by tap on Video button) and it successfully starts publishing. I experience the same issue with conference calls on iOS simulator in foreground app state - it never starts publishing.

However, in the foreground this flow works perfect. In the logs I can see the same commands as in background, but at the end of "offer-answer" communications in foreground client receives "publish_started" command.

Also, p2p calls works perfect both in background and foreground states.

Thanks