How to audio call record functionality in WebRTC iOS Swift

We have recorded presenter audio with AVAudioSession, but we can't get to the receiver audio stream.

we are facing the issue of getting remote audio streaming.

please let me know how to get the receiver audio stream and also how to merge both audios. (presenter and receiver)

if possible with AVAudioSession otherwise WebRTC built in some functionality like RTCAudioSession please let me know.

please find below the record presenter audio with AVAudioSession code:

func setAVAudioSession() {
    recordingSession = AVAudioSession.sharedInstance()
    do {
        try recordingSession.setCategory(AVAudioSessionCategoryPlayAndRecord, mode: AVAudioSessionModeVoiceChat, options: [])
        try recordingSession.setActive(true)
        recordingSession.requestRecordPermission() { [unowned self] allowed in
            DispatchQueue.main.async {
                if allowed {
                    self.startRecording()
                } else {
                    // failed to record!
                }
            }
        }
    } catch {
        // failed to record!
    }
}

func startRecording() {
    let audioFilename = getDocumentsDirectory().appendingPathComponent("recording\(Date().description).aac")
    let settings = [
        AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
        AVSampleRateKey: 12000,
        AVNumberOfChannelsKey: 2,
        AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
    ]
    do {
        audioRecorder = try AVAudioRecorder(url: audioFilename, settings: settings)
        audioRecorder.delegate = self
        audioRecorder.record()
        recordButton.setTitle("Tap to Stop", for: .normal)
    } catch {
        finishRecording(success: false)
    }
}

Thanks in advance.