example of RTCDataChannel implementation about webrtc-ios HOT 3 CLOSED

private var peerConnections: [String: RTCPeerConnection] = [String: RTCPeerConnection]()

    private func _createOffer(hostID: String) {

        guard let peerConnection = getPeerConnection(hostID) else {
            print("missing peer connection")
            return
        }
        
        // 1. offer
        peerConnection.offer(for: WebRTCUtil.mediaStreamConstraints(), completionHandler: { [weak self] (description, error) in
            
            guard let description = description else {
                print("----- no description ----")
                return
            }

            // 2.SDP
            peerConnection.setLocalDescription(description, completionHandler: { (error) in
                guard let this = self else {
                    print("missin self")
                    return }
         
            })
            
            // 3. peerConnection(_ peerConnection: RTCPeerConnection, didChange newState: RTCIceGatheringState)
            // complete offer
        })
    }