Low-Level Networking on watchOS for Duplex audio streaming

Did you watch WWDC 2019 Session 716 Streaming Audio on watchOS 6? I explains how the low-level networking capability is tied to the presence of an active audio session:

Once your application has an active audio session, all of the networking APIs are available to retrieve audio content.

I suspect that you’ve failed to set that up, and so low-level networking is blocked.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

I did watch WWDC 2019 Session 716 and understand that an active audio session is key to unlocking low‑level networking on watchOS. I’m configuring my audio session and engine as follows:

private func configureAudioSession(completion: @escaping (Bool) -> Void) {
    let audioSession = AVAudioSession.sharedInstance()
    do {
        try audioSession.setCategory(.playAndRecord, mode: .voiceChat, options: [])
        try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
        // Retrieve sample rate and configure the audio format.
        let sampleRate = audioSession.sampleRate
        print("Active hardware sample rate: \(sampleRate)")
        audioFormat = AVAudioFormat(standardFormatWithSampleRate: sampleRate, channels: 1)
        // Configure the audio engine.
        audioInputNode = audioEngine.inputNode
        audioEngine.attach(audioPlayerNode)
        audioEngine.connect(audioPlayerNode, to: audioEngine.mainMixerNode, format: audioFormat)
        
        try audioEngine.start()
        completion(true)
    } catch {
        print("Error configuring audio session: \(error.localizedDescription)")
        completion(false)
    }
}
 
private func setupUDPConnection() {
    let parameters = NWParameters.udp
    parameters.includePeerToPeer = true
    connection = NWConnection(host: "***.***.xxxxx.***", port: 0000, using: parameters)
    setupNWConnectionHandlers()
}
 
   
    private func setupTCPConnection() {
        let parameters = NWParameters.tcp
        connection = NWConnection(host: "***.***.xxxxx.***", port: 0000, using: parameters)
        setupNWConnectionHandlers()
    }
 
    
    private func setupWebSocketConnection() {
        guard let url = URL(string: "ws://***.***.xxxxx.***:0000") else {
            print("Invalid WebSocket URL")
            return
        }
 
        let session = URLSession(configuration: .default)
        webSocketTask = session.webSocketTask(with: url)
        webSocketTask?.resume()
        print("WebSocket connection initiated")
        sendAudioToServer()
        receiveDataFromServer()
        sendWebSocketPing(after: 0.6)
    }
 
    private func setupNWConnectionHandlers() {
        connection?.stateUpdateHandler = { [weak self] state in
            DispatchQueue.main.async {
                switch state {
                case .ready:
                    print("Connected (NWConnection)")
                    self?.isConnected = true
                    self?.failToConnect = false
                    self?.receiveDataFromServer()
                    self?.sendAudioToServer()
                case .waiting(let error), .failed(let error):
 
                    print("Connection error: \(error.localizedDescription)")
                    DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
                        self?.setupNetwork()
                    }
                case .cancelled:
                    print("NWConnection cancelled")
                    self?.isConnected = false
 
                default:
                    break
                }
            }
        }
        connection?.start(queue: .main)
    }
 

I’m using the .playAndRecord category with .voiceChat mode because my app requires duplex streaming—capturing audio to send to a server and playing back the incoming audio. Despite this setup and ensuring that the audio engine is running, my low-level connections (UDP, TCP, and WebSocket via NWConnection/URLSessionWebSocketTask) remain in a “waiting” state and eventually fail with Error 50 on a real Apple Watch.

I'm not using the simple activation snippet with an empty options array because it ask for audio route but i wanted to perform duplex audio streaming with default speaker and mic.

I am reaching out to seek further assistance regarding the challenges I've been experiencing with establishing a UDP, TCP & web socket connection on watchOS using NWConnection for duplex audio streaming. Despite implementing the recommendations provided earlier, I am still encountering difficulties. Or duplex audio streaming not possible on apple watch?