示例：语音助手
本示例构建一个语音对话 app：录制语音、转写语音、将转写文本发送给本地 LLM、合成回复并播放音频。
架构
Microphone -> STTEngine -> LLMEngine -> TTSEngine -> Speaker
当你需要一个无需将语音或 prompt 发送到服务器即可运行的私有助手时，可以使用这种形态。
前置条件
- 已通过 Swift Package Manager 添加 Edge Kit。
- 同一 package setup 中可用的 Edge Voice，用于麦克风录音。
- STT、LLM 和 TTS 模型的本地模型目录。
- App 的
Info.plist中包含麦克风用途说明。
<key>NSMicrophoneUsageDescription</key>
<string>This app records your voice to run private on-device transcription.</string>
完整代码
创建新的 SwiftUI 应用 target，添加 Edge Kit，并将 App 代码替换为以下内容：
import AVFoundation
import EdgeInference
import EdgeVoice
import SwiftUI
@main
struct VoiceAssistantExampleApp: App {
var body: some Scene {
WindowGroup {
VoiceAssistantView()
}
}
}
struct VoiceAssistantView: View {
@StateObject private var model = VoiceAssistantViewModel()
var body: some View {
VStack(alignment: .leading, spacing: 14) {
Group {
TextField("STT model directory", text: $model.sttModelPath)
TextField("LLM model directory", text: $model.llmModelPath)
TextField("TTS model directory", text: $model.ttsModelPath)
}
.textFieldStyle(.roundedBorder)
HStack {
Button(model.isReady ? "Models Loaded" : "Load Models") {
Task { await model.loadModels() }
}
.disabled(model.isLoading)
Button(model.isRecording ? "Stop" : "Record") {
Task { await model.toggleRecording() }
}
.disabled(!model.isReady || model.isProcessing)
}
Text(model.phase)
.font(.caption)
.foregroundStyle(.secondary)
VStack(alignment: .leading, spacing: 8) {
Text("Transcript")
.font(.headline)
Text(model.transcript.isEmpty ? "No speech yet." : model.transcript)
.textSelection(.enabled)
}
VStack(alignment: .leading, spacing: 8) {
Text("Assistant")
.font(.headline)
Text(model.reply.isEmpty ? "No reply yet." : model.reply)
.textSelection(.enabled)
}
Spacer()
}
.padding()
}
}
@MainActor
final class VoiceAssistantViewModel: ObservableObject {
@Published var sttModelPath = "\(NSHomeDirectory())/Models/Qwen3-ASR"
@Published var llmModelPath = "\(NSHomeDirectory())/Models/Qwen3.5-9B-4bit"
@Published var ttsModelPath = "\(NSHomeDirectory())/Models/Qwen3-TTS"
@Published var transcript = ""
@Published var reply = ""
@Published var phase = "Load models to begin."
@Published var isLoading = false
@Published var isReady = false
@Published var isProcessing = false
private let recorder = AudioRecorder()
private let stt = STTEngine()
private let llm = LLMEngine()
private let tts = TTSEngine()
private var history: [ChatMessage] = [
.system("You are a concise voice assistant. Keep replies short.")
]
private var playbackEngine: AVAudioEngine?
private var playerNode: AVAudioPlayerNode?
var isRecording: Bool {
recorder.isRecording
}
func loadModels() async {
guard !isLoading else { return }
isLoading = true
phase = "Loading models..."
defer { isLoading = false }
do {
try await stt.loadLocal(directory: URL(fileURLWithPath: sttModelPath))
try await llm.loadLocal(directory: URL(fileURLWithPath: llmModelPath))
try await tts.loadLocal(directory: URL(fileURLWithPath: ttsModelPath))
isReady = true
phase = "Ready"
} catch {
isReady = false
phase = "Load failed: \(error.localizedDescription)"
}
}
func toggleRecording() async {
if recorder.isRecording {
guard let audioURL = recorder.stopRecording() else { return }
await answer(audioURL: audioURL)
} else {
do {
_ = try await recorder.startRecording()
phase = "Listening..."
} catch {
phase = "Recording failed: \(error.localizedDescription)"
}
}
}
private func answer(audioURL: URL) async {
guard isReady, !isProcessing else { return }
isProcessing = true
defer { isProcessing = false }
do {
phase = "Transcribing..."
let result = try await stt.transcribe(audioURL: audioURL)
let userText = result.text.trimmingCharacters(in: .whitespacesAndNewlines)
transcript = userText
phase = "Generating..."
let request = history + [.user(userText)]
let assistantText = try await llm.generateOnce(
messages: request,
parameters: EdgeGenerateParameters(maxTokens: 160)
)
reply = assistantText
history = request + [.assistant(assistantText)]
phase = "Speaking..."
let audio = try await tts.speak(assistantText)
try play(audio)
} catch {
phase = "Failed: \(error.localizedDescription)"
}
}
private func play(_ result: AudioResult) throws {
guard !result.samples.isEmpty else { return }
let format = AVAudioFormat(
commonFormat: .pcmFormatFloat32,
sampleRate: Double(result.sampleRate),
channels: 1,
interleaved: false
)!
let frameCount = AVAudioFrameCount(result.samples.count)
guard let buffer = AVAudioPCMBuffer(
pcmFormat: format,
frameCapacity: frameCount
) else {
return
}
buffer.frameLength = frameCount
result.samples.withUnsafeBufferPointer { samples in
if let base = samples.baseAddress,
let channel = buffer.floatChannelData?[0] {
channel.update(from: base, count: samples.count)
}
}
let engine = AVAudioEngine()
let player = AVAudioPlayerNode()
engine.attach(player)
engine.connect(player, to: engine.mainMixerNode, format: format)
try engine.start()
player.play()
player.scheduleBuffer(buffer, at: nil, options: .interrupts) { [weak self] in
Task { @MainActor in
self?.phase = "Ready"
}
}
playbackEngine = engine
playerNode = player
}
}
关键概念
- 顺序运行三个模型调用：转写、生成、合成。
- 为语音保持较短回复，让 TTS 可以快速开始并完成。
- 对对话历史复用同一个
LLMEngine。 - 在计划支持的最低配置设备上测试完整 pipeline。
- 提供可见的录音状态和清晰的麦克风权限文案。