createMediaSenders.swift

private func createMediaSenders() {
    let streamId = "stream"
    
    // Audio
    let audioTrack = self.createAudioTrack()
    self.peerConnection!.add(audioTrack, streamIds: [streamId])
    
    // Video
    let videoTrack = self.createVideoTrack()
    self.localVideoTrack = videoTrack
    self.peerConnection!.add(videoTrack, streamIds: [streamId])
    self.remoteVideoTrack = self.peerConnection!.transceivers.first { $0.mediaType == .video }?.receiver.track as? RTCVideoTrack
    
    // Data
    if let dataChannel = createDataChannel() {
      dataChannel.delegate = self
      self.localDataChannel = dataChannel
    }
  }
  
  private func createAudioTrack() -> RTCAudioTrack {
    let audioConstrains = RTCMediaConstraints(mandatoryConstraints: nil, optionalConstraints: nil)
    let audioSource = WebRTCClient.factory.audioSource(with: audioConstrains)
    let audioTrack = WebRTCClient.factory.audioTrack(with: audioSource, trackId: "audio0")
    return audioTrack
  }
  
  private func createVideoTrack() -> RTCVideoTrack {
    let videoSource = WebRTCClient.factory.videoSource()
    
    #if TARGET_OS_SIMULATOR
    self.videoCapturer = RTCFileVideoCapturer(delegate: videoSource)
    #else
    self.videoCapturer = RTCCameraVideoCapturer(delegate: videoSource)
    #endif
    
    let videoTrack = WebRTCClient.factory.videoTrack(with: videoSource, trackId: "video0")
    return videoTrack
  }
  
  // MARK: Data Channels
  private func createDataChannel() -> RTCDataChannel? {
    let config = RTCDataChannelConfiguration()
    guard let dataChannel = self.peerConnection!.dataChannel(forLabel: "WebRTCData", configuration: config) else {
      debugPrint("Warning: Couldn't create data channel.")
      return nil
    }
    return dataChannel
  }