fixed some bugs on ios

ios/OralTrainer/Services/AudioRecorderSession.swift

@@ -0,0 +1,159 @@
+import AVFoundation
+import Foundation
+
+enum AudioRecorderSessionError: LocalizedError {
+    case inputUnavailable
+    case startFailed
+    case conversionFailed
+
+    var errorDescription: String? {
+        switch self {
+        case .inputUnavailable:
+            return "未检测到麦克风输入"
+        case .startFailed:
+            return "无法开始录制：请确认麦克风未被其他应用占用后重试"
+        case .conversionFailed:
+            return "录音文件转码失败"
+        }
+    }
+}
+
+/// 基于 AVAudioEngine 的录音会话。
+///
+/// AVAudioRecorder 在 iOS 26 真机上存在 record() 恒返回 false 的已知问题
+/// （Apple 开发者论坛多个报告），因此这里改用 AVAudioEngine 采集 PCM，
+/// 停止录音时再转码为 16kHz 单声道 AAC（m4a），与服务端评测接口保持一致。
+final class AudioRecorderSession {
+    private let engine = AVAudioEngine()
+    private let outputURL: URL
+    private let pcmURL: URL
+    private var inputFile: AVAudioFile?
+    private var tapInstalled = false
+
+    private(set) var isRunning = false
+    private(set) var recordDuration: TimeInterval = 0
+
+    /// 本次录音的原始 PCM 文件（caf），停止录音后仍保留，
+    /// 供配音合成直接合并，避免在 iOS 26 上读回 AAC（AVAudioFile 存在 'fmt?' 问题）。
+    var rawRecordingURL: URL { pcmURL }
+
+    init(outputURL: URL) {
+        self.outputURL = outputURL
+        let stamp = Int(Date().timeIntervalSince1970 * 1000)
+        self.pcmURL = FileManager.default.temporaryDirectory
+            .appendingPathComponent("raw-\(stamp).caf")
+    }
+
+    /// 激活音频会话并开始采集。失败时抛出错误，可在重新激活会话后重试。
+    func start() throws {
+        let session = AVAudioSession.sharedInstance()
+        try session.setCategory(.playAndRecord, mode: .default, options: [.defaultToSpeaker])
+        try session.setActive(true)
+        guard session.isInputAvailable else {
+            throw AudioRecorderSessionError.inputUnavailable
+        }
+
+        let input = engine.inputNode
+        if !tapInstalled {
+            let inputFormat = input.outputFormat(forBus: 0)
+            guard inputFormat.sampleRate > 0, inputFormat.channelCount > 0 else {
+                throw AudioRecorderSessionError.inputUnavailable
+            }
+            let file = try AVAudioFile(forWriting: pcmURL, settings: inputFormat.settings)
+            inputFile = file
+            input.installTap(onBus: 0, bufferSize: 4096, format: inputFormat) { [weak self] buffer, _ in
+                guard let self = self else { return }
+                do {
+                    try self.inputFile?.write(from: buffer)
+                } catch {
+                    // 单个缓冲写入失败时忽略，继续录音
+                }
+            }
+            tapInstalled = true
+        }
+        engine.prepare()
+        do {
+            try engine.start()
+        } catch {
+            throw AudioRecorderSessionError.startFailed
+        }
+        isRunning = true
+    }
+
+    /// 停止录音，将 PCM 转码为 m4a 写入 outputURL。
+    func stop() throws {
+        guard isRunning else { return }
+        engine.inputNode.removeTap(onBus: 0)
+        engine.stop()
+        isRunning = false
+        tapInstalled = false
+        inputFile = nil
+        try finalizeToAAC()
+    }
+
+    /// 放弃本次录音并清理临时文件。
+    func cancel() {
+        if isRunning {
+            engine.inputNode.removeTap(onBus: 0)
+            engine.stop()
+            isRunning = false
+            tapInstalled = false
+            inputFile = nil
+        }
+        try? FileManager.default.removeItem(at: pcmURL)
+        try? FileManager.default.removeItem(at: outputURL)
+    }
+
+    private func finalizeToAAC() throws {
+        let inputFile = try AVAudioFile(forReading: pcmURL)
+        recordDuration = Double(inputFile.length) / inputFile.processingFormat.sampleRate
+        let outputSettings: [String: Any] = [
+            AVFormatIDKey: kAudioFormatMPEG4AAC,
+            AVSampleRateKey: 16_000,
+            AVNumberOfChannelsKey: 1,
+        ]
+        let outputFile = try AVAudioFile(forWriting: outputURL, settings: outputSettings)
+        guard let converter = AVAudioConverter(from: inputFile.processingFormat, to: outputFile.processingFormat) else {
+            throw AudioRecorderSessionError.conversionFailed
+        }
+        let inputBlock: AVAudioConverterInputBlock = { inNumPackets, outStatus in
+            if inputFile.framePosition >= inputFile.length {
+                outStatus.pointee = .endOfStream
+                return nil
+            }
+            let remaining = inputFile.length - inputFile.framePosition
+            let frames = AVAudioFrameCount(min(inNumPackets, AVAudioFrameCount(remaining)))
+            guard frames > 0,
+                  let buffer = AVAudioPCMBuffer(pcmFormat: inputFile.processingFormat, frameCapacity: frames) else {
+                outStatus.pointee = .noDataNow
+                return nil
+            }
+            do {
+                try inputFile.read(into: buffer)
+                outStatus.pointee = .haveData
+                return buffer
+            } catch {
+                outStatus.pointee = .noDataNow
+                return nil
+            }
+        }
+        let capacity = AVAudioFrameCount(min(4096, max(1, Int(inputFile.length))))
+        guard let outputBuffer = AVAudioPCMBuffer(pcmFormat: outputFile.processingFormat, frameCapacity: capacity) else {
+            throw AudioRecorderSessionError.conversionFailed
+        }
+        while true {
+            var conversionError: NSError?
+            let status = converter.convert(to: outputBuffer, error: &conversionError, withInputFrom: inputBlock)
+            switch status {
+            case .haveData:
+                try outputFile.write(from: outputBuffer)
+            case .inputRanDry, .endOfStream:
+                return
+            case .error:
+                throw conversionError ?? AudioRecorderSessionError.conversionFailed
+            default:
+                return
+            }
+        }
+    }
+}