getting audio data as byte data from Microphone in Swift

Question

I am new swift development, I am trying get audio from microphone as a byte Array, I get permission below code, and I am trying get byte Array in startVoice function in below, but When I run real device(iPhone 6s) it doesn't get audio data from microphone, how can I get audio data as a byte data in real time?

func permissions() {
    print("Permissions")
    
    switch AVAudioSession.sharedInstance().recordPermission {
    case AVAudioSession.RecordPermission.granted:
        print("Permission granted")
    case AVAudioSession.RecordPermission.denied:
        print("Pemission denied")
    case AVAudioSession.RecordPermission.undetermined:
        print("Request permission here")
        AVAudioSession.sharedInstance().requestRecordPermission({ (granted) in
            // Handle granted
        })
    }

}

func startVoice() {
    let engine = AVAudioEngine()
    let bus = 0
    let inputNode = engine.inputNode

    let equalizer = AVAudioUnitEQ(numberOfBands: 2)

    equalizer.bands[0].filterType = .lowPass
    equalizer.bands[0].frequency = 3000
    equalizer.bands[0].bypass = false

    equalizer.bands[1].filterType = .highPass
    equalizer.bands[1].frequency = 1000
    equalizer.bands[1].bypass = false
    engine.attach(equalizer) //Attach equalizer

    // Connect nodes
    engine.connect(inputNode, to: equalizer, format: inputNode.inputFormat(forBus: 0))
    engine.connect(equalizer, to: engine.mainMixerNode, format: inputNode.inputFormat(forBus: 0))

    // call before creating converter because this changes the mainMixer's output format
    engine.prepare()

    let outputFormat = AVAudioFormat(commonFormat: .pcmFormatInt16,
                                     sampleRate: 1000,
                                     channels: 1,
                                     interleaved: false)!

    // Downsampling converter
    guard let converter: AVAudioConverter = AVAudioConverter(from: engine.mainMixerNode.outputFormat(forBus: 0), to: outputFormat) else {
        print("Can't convert in to this format")
        return
    }

    engine.mainMixerNode.installTap(onBus: bus, bufferSize: 2688, format: nil) { (buffer, time) in
        var newBufferAvailable = true
        
        let inputCallback: AVAudioConverterInputBlock = { inNumPackets, outStatus in
            if newBufferAvailable {
                outStatus.pointee = .haveData
                newBufferAvailable = false
                return buffer
            } else {
                outStatus.pointee = .noDataNow
                return nil
            }
        }
        
        
        let convertedBuffer = AVAudioPCMBuffer(pcmFormat: outputFormat, frameCapacity: AVAudioFrameCount(outputFormat.sampleRate) * buffer.frameLength / AVAudioFrameCount(buffer.format.sampleRate))!
        
        var error: NSError?
        let status = converter.convert(to: convertedBuffer, error: &error, withInputFrom: inputCallback)
        assert(status != .error)
        
        
        if status == .haveData {
            // Process with converted buffer
        }
    }

    do {
        try engine.start()
    } catch {
        print("Can't start the engine: \(error)")
    }
    
}