MCSessionDelegate - Getting No Bytes When Receiving Stream - ios

Question

i'm pretty new to Swift/iOS, just started learning that a couple days ago. I'm using Swift 3 and want to develop two iPhone apps that can send audio stream from microphone to other iPhone devices using Multi-peer Connectivity. The first app would be the speaker's app and the other would be the listener's app.
Previously, I learned how to advertise, browse, and invite peers from this useful tutorial
and I learned how to get audio data from microphone and convert them to bytes from this answer and this answer. Thanks a lot to Rhythmic Fistman.
So, my code is combination of what those articles include.
This is ViewController of listener app
import UIKit
import MultipeerConnectivity
import AVFoundation
class ColorSwitchViewController: UIViewController {
#IBOutlet weak var connectionsLabel: UILabel!
let colorService = ColorServiceManager()
var engine = AVAudioEngine()
let player = AVAudioPlayerNode()
// Somewhere, schedule the stream in the mainRunLoop, set the delegate and open it. Choose the peer that you want to connect
var inputStream = InputStream()
var inputStreamIsSet: Bool!
var outputStreamIsSet: Bool!
public let peerID = MCPeerID(displayName: UIDevice.current.name)
//MARK: Private Functions
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func copyAudioBufferBytes(_ audioBuffer: AVAudioPCMBuffer) -> [UInt8] {
let srcLeft = audioBuffer.floatChannelData![0]
let bytesPerFrame = audioBuffer.format.streamDescription.pointee.mBytesPerFrame
let numBytes = Int(bytesPerFrame * audioBuffer.frameLength)
// initialize bytes to 0 (how to avoid?)
var audioByteArray = [UInt8] (repeating: 0, count: numBytes)
// copy data from buffer
srcLeft.withMemoryRebound(to: UInt8.self, capacity: numBytes) { srcByteData in
audioByteArray.withUnsafeMutableBufferPointer {
$0.baseAddress!.initialize(from: srcByteData, count: numBytes)
}
}
return audioByteArray
}
func bytesToAudioBuffer(_ buf: [UInt8]) -> AVAudioPCMBuffer {
let fmt = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 1, interleaved: true)
let frameLength = UInt32(buf.count) / fmt.streamDescription.pointee.mBytesPerFrame
let audioBuffer = AVAudioPCMBuffer(pcmFormat: fmt, frameCapacity: frameLength)
audioBuffer.frameLength = frameLength
let dstLeft = audioBuffer.floatChannelData![0]
buf.withUnsafeBufferPointer {
let src = UnsafeRawPointer($0.baseAddress!).bindMemory(to: Float.self, capacity: Int(frameLength))
dstLeft.initialize(from: src, count: Int(frameLength))
}
return audioBuffer
}
override func viewDidLoad() {
super.viewDidLoad()
colorService.delegate = self
}
#IBAction func redTapped() {
self.change(color: .red)
colorService.send(colorName: "red")
}
#IBAction func yellowTapped() {
self.change(color: .yellow)
colorService.send(colorName: "yellow")
}
func change(color : UIColor) {
UIView.animate(withDuration: 0.2) {
self.view.backgroundColor = color
}
}
}
extension ColorSwitchViewController : ColorServiceManagerDelegate {
func connectedDevicesChanged(manager: ColorServiceManager, connectedDevices: [String]) {
OperationQueue.main.addOperation {
self.connectionsLabel.text = "Connections: \(connectedDevices)"
}
}
func colorChanged(manager: ColorServiceManager, colorString: String) {
OperationQueue.main.addOperation {
switch colorString {
case "red":
self.change(color: .red)
case "yellow":
self.change(color: .yellow)
default:
NSLog("%#", "Unknown color value received: \(colorString)")
}
}
}
func streamReceived(manager: ColorServiceManager, stream: InputStream, streamName: String, fromPeer: MCPeerID) {
NSLog("%#", "name " + fromPeer.displayName)
if streamName == "stream" && fromPeer != peerID {
NSLog("%#", "voice received")
stream.schedule(in: RunLoop.current, forMode: .defaultRunLoopMode)
stream.open()
var bytes = [UInt8](repeating: 0, count: 17640)
if (stream.hasBytesAvailable == true) {
NSLog("%#", "has bytes available...")
} else {
NSLog("%#", "has NO byte ...")
}
let result = stream.read(&bytes, maxLength: bytes.count)
if result == 0 {
print("Stream at capacity")
} else if result == -1 {
print("Operation failed: \(String(describing: stream.streamError))")
} else {
print("The number of bytes read is \(result)")
}
let audioBuffer = self.bytesToAudioBuffer(bytes) //Here is where the app crashes
engine.attach(player)
let outputFormat = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 1, interleaved: true)
engine.connect(player, to: engine.mainMixerNode, format: outputFormat)
do {
try engine.start()
player.scheduleBuffer(audioBuffer, completionHandler: nil)
player.play()
} catch let error {
print(error.localizedDescription)
}
}
}
}
And the ViewController of the speaker app is similar except that it contains code for sending the stream and doesn't contain code for receiving
// ....
override func viewDidLoad() {
super.viewDidLoad()
colorService.delegate = self
}
func startStream() {
let input = engine.inputNode!
engine.attach(player)
let bus = 0
let inputFormat = input.inputFormat(forBus: bus)
engine.connect(player, to: engine.mainMixerNode, format: inputFormat)
NSLog("%#", "sendStream: to \(self.colorService.session.connectedPeers.count) peers")
if self.colorService.session.connectedPeers.count > 0 {
do {
let outputStream = try self.colorService.session.startStream(withName: "stream", toPeer: self.colorService.session.connectedPeers.first!)
outputStream.schedule(in: RunLoop.main, forMode:RunLoopMode.defaultRunLoopMode)
outputStream.open()
let bus = 0
let inputFormat = input.inputFormat(forBus: bus)
input.installTap(onBus: bus, bufferSize: 2048, format: inputFormat, block: {
(buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in
self.player.scheduleBuffer(buffer)
let audioBuffer = self.copyAudioBufferBytes(buffer)
// NSLog("%#", "speaking...")
let result = outputStream.write(audioBuffer, maxLength: audioBuffer.count)
if result == 0 {
print("Stream at capacity")
} else if result == -1 {
print("Operation failed: \(String(describing: outputStream.streamError))")
} else {
print("The number of bytes written is \(result)")
}
})
try! engine.start()
player.play()
}
catch let error {
NSLog("%#", "Error for sending: \(error)")
}
}
}
func stopStream() {
engine.inputNode?.removeTap(onBus: 0)
player.stop()
}
#IBAction func redTapped() {
self.change(color: .red)
colorService.send(colorName: "red")
self.startStream()
}
#IBAction func yellowTapped() {
self.change(color: .yellow)
colorService.send(colorName: "yellow")
self.stopStream()
}
// ...
Unfortunately, on the listener side, i get the app receiving the stream with no bytes available. NSLog("%#", "has NO byte ...") was called. I wonder if the listener app really receive the audio stream or not.
So, What's my mistake here? Any helps would be appreciated. Thank you in advance.