我对Swift / iOS很陌生，几天前刚刚开始学习。我正在使用Swift 3并希望开发两个iPhone应用程序，可以使用多对等连接将音频流从麦克风发送到其他iPhone设备。第一个应用程序将是发言人的应用程序，另一个应用程序将是聆听者的应用程序。
之前，我学习了如何通过此useful tutorial
宣传，浏览和邀请同行我学会了如何从麦克风获取音频数据并将其转换为此answer和此answer的字节数。非常感谢Rhythmic Fistman。
所以，我的代码是这些文章包含的内容的组合。
这是侦听器应用程序的ViewController
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)
}
}
}
}
扬声器应用程序的ViewController类似，只是它包含用于发送流的代码，并且不包含用于接收的代码
// ....
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()
}
// ...
不幸的是，在侦听器方面，我得到的应用程序接收没有可用字节的流。 NSLog("%@", "has NO byte ...")被召唤了。我想知道听众应用程序是否真的收到了音频流。
那么，我的错误是什么？任何帮助将不胜感激。先感谢您。