下午好，亲爱的读者！ 前段时间，我决定尝试在设备之间录制和传输录制的声音。 作为传输录制的声音的一种方法，该选择落在
MultipeerConnectivity框架上。 在本文中，我将告诉您如何执行此操作。
首先，我们需要两个设备来记录和播放声音。 因此，我们需要编写一个类来执行这些操作。
来自设备的实时音频录制
为了录制音频，
使用了
AVFoundation框架随附的常规
AVAudioEngine和
AVAudioMixerNode 。
录音示例：
final class Recorder { private let engine = AVAudioEngine() private let mixer = AVAudioMixerNode() var onRecordedAction: ((Data) -> Void)? init() { setupAudioSession() } private func setupAudioSession() { let audioSession = AVAudioSession.sharedInstance() do { try audioSession.setCategory(.record) try audioSession.setMode(.measurement) try audioSession.setActive(true) } catch { debugPrint(error.localizedDescription) } } func startRecording() { let input = engine.inputNode let inputFormat = input.outputFormat(forBus: 0) engine.attach(mixer) engine.connect(input, to: mixer, format: inputFormat) mixer.installTap(onBus: 0, bufferSize: 1024, format: mixer.outputFormat(forBus: 0)) { [weak self] buffer, _ in self?.onRecordedAction?(buffer.data) } engine.prepare() do { try engine.start() } catch { debugPrint(error.localizedDescription) } } func stopRecording() { engine.stop() } }
通常，没有任何异常，在混合器的帮助下，我们获取实时数据并将其发送到我们的onRecodedAction函数。 为了进一步传输我们录制的音频，我们需要将其转换为数据。 为此，我准备了下一个扩展。
将
PCMBuffer转换为
Data的示例：
extension AVAudioPCMBuffer { var data: Data { let channels = UnsafeBufferPointer(start: floatChannelData, count: 1) let data = Data(bytes: channels[0], count: Int(frameCapacity * format.streamDescription.pointee.mBytesPerFrame)) return data } }
播放收到的音频
简而言之，使用相同的框架来播放音频，结果，没有什么复杂的事情，我们仅创建一个节点并将其分配给引擎，然后将数据转换回
PCMBuffer并将其提供给我们的节点进行播放。
播放示例：
final class Player { private let engine = AVAudioEngine() private var playerNode = AVAudioPlayerNode() init() { setupAudioSession() } private func setupAudioSession() { let audioSession = AVAudioSession.sharedInstance() do { try audioSession.setCategory(.playback) try audioSession.setActive(true) } catch { debugPrint(error.localizedDescription) } } private func setupPlayer(buffer: AVAudioPCMBuffer) { engine.attach(playerNode) engine.connect(playerNode, to: engine.mainMixerNode, format: buffer.format) engine.prepare() } private func tryStartEngine() { do { try engine.start() } catch { debugPrint(error.localizedDescription) } } func addPacket(packet: Data) { guard let format = AVAudioFormat.common, let buffer = packet.pcmBuffer(format: format) else { debugPrint("Cannot convert buffer from Data") return } if !engine.isRunning { setupPlayer(buffer: buffer) tryStartEngine() playerNode.play() } playerNode.volume = 1 playerNode.scheduleBuffer(buffer, completionHandler: nil) } }
将
数据转换回
PCMBuffer和我们的
AVAudioFormat播放音频的示例扩展：
private extension Data { func pcmBuffer(format: AVAudioFormat) -> AVAudioPCMBuffer? { let streamDesc = format.streamDescription.pointee let frameCapacity = UInt32(count) / streamDesc.mBytesPerFrame guard let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: frameCapacity) else { return nil } buffer.frameLength = buffer.frameCapacity let audioBuffer = buffer.audioBufferList.pointee.mBuffers withUnsafeBytes { addr in guard let baseAddress = addr.baseAddress else { return } audioBuffer.mData?.copyMemory(from: baseAddress, byteCount: Int(audioBuffer.mDataByteSize)) } return buffer } } extension AVAudioFormat { static let common = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 1, interleaved: false) }
将录制的音频从设备传输到设备
好了，最后，我们来
谈谈最重要的事情-使用
MultipeerConnectivity在设备之间传输记录的音频。 为此，我们需要创建一个
MCPeerID对象（将确定我们的设备）以及
MCNearbyServiceAdvertiser和
MCNearbyServiceBrowser类的两个实例，这些实例将用于搜索设备，以便其他设备可以找到我们（也接受来自其他设备的连接请求）。 我们还创建了一个会话，通过该会话我们将传输记录的音频并“操纵”我们的设备。
传输和接收数据的示例类：
private struct Constants { static var serviceType = "bn-radio" static var timeOut: Double = 10 } final class Connectivity: NSObject { private var advertiser: MCNearbyServiceAdvertiser? = nil private var browser: MCNearbyServiceBrowser? = nil private let peerID: MCPeerID private let session: MCSession private var invitationHandler: ((Bool, MCSession) -> Void)? = nil var onDeviceFoundedAction: ((MCPeerID) -> Void)? var onDeviceLostedAction: ((MCPeerID) -> Void)? var onInviteAction: ((MCPeerID) -> Void)? var onConnectingAction: (() -> Void)? var onConnectedAction: (() -> Void)? var onDisconnectedAction: (() -> Void)? var onPacketReceivedAction: ((Data) -> Void)? init(deviceID: String) { peerID = MCPeerID(displayName: deviceID) session = MCSession(peer: peerID, securityIdentity: nil, encryptionPreference: .none) super.init() session.delegate = self } func startHosting() { advertiser = MCNearbyServiceAdvertiser(peer: peerID, discoveryInfo: nil, serviceType: Constants.serviceType) advertiser?.delegate = self advertiser?.startAdvertisingPeer() } func findHost() { browser = MCNearbyServiceBrowser(peer: peerID, serviceType: Constants.serviceType) browser?.delegate = self browser?.startBrowsingForPeers() } func stop() { advertiser?.stopAdvertisingPeer() browser?.stopBrowsingForPeers() } func invite(peerID: MCPeerID) { browser?.invitePeer(peerID, to: session, withContext: nil, timeout: Constants.timeOut) } func handleInvitation(isAccepted: Bool) { invitationHandler?(isAccepted, session) } func send(data: Data) { try? self.session.send(data, toPeers: session.connectedPeers, with: .unreliable) } } extension Connectivity: MCSessionDelegate { func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState) { switch state { case .connecting: onConnectingAction?() case .connected: onConnectedAction?() case .notConnected: onDisconnectedAction?() @unknown default: debugPrint("Error during session state changed on: \(state)") } } func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID) { onPacketReceivedAction?(data) } func session(_ session: MCSession, didReceive stream: InputStream, withName streamName: String, fromPeer peerID: MCPeerID) { } func session(_ session: MCSession, didStartReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, with progress: Progress) { } func session(_ session: MCSession, didFinishReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, at localURL: URL?, withError error: Error?) { } func session(_ session: MCSession, didReceiveCertificate certificate: [Any]?, fromPeer peerID: MCPeerID, certificateHandler: @escaping (Bool) -> Void) { certificateHandler(true) } } extension Connectivity: MCNearbyServiceAdvertiserDelegate { func advertiser(_ advertiser: MCNearbyServiceAdvertiser, didReceiveInvitationFromPeer peerID: MCPeerID, withContext context: Data?, invitationHandler: @escaping (Bool, MCSession?) -> Void) { self.invitationHandler = invitationHandler onInviteAction?(peerID) } } extension Connectivity: MCNearbyServiceBrowserDelegate { func browser(_ browser: MCNearbyServiceBrowser, foundPeer peerID: MCPeerID, withDiscoveryInfo info: [String : String]?) { onDeviceFoundedAction?(peerID) } func browser(_ browser: MCNearbyServiceBrowser, lostPeer peerID: MCPeerID) { onDeviceLostedAction?(peerID) } }
我决定不上载我的应用程序的所有代码，因为我认为如何使用它的本质就足够了，如示例所示。 我同意有些事情可以用不同的方式实现，但是在这种情况下，我使用了我需要的方法。
在使用
MultipeerConnectivity的过程中 ，发现了一些负面方面，例如连接的距离，因此，如果您需要持续传输类似于实时音频的内容，我不建议使用这种数据传输方法。