iOS录音因来电或闹钟中断如何处理？

Question

在iOS应用开发中，使用AVAudioRecorder进行录音时，常遇到因来电或闹钟触发导致录音被意外中断的问题。即使应用进入后台，系统会暂停音频会话，造成录音停止且无法自动恢复。开发者需监听AVAudioSession.interruptionNotification通知，正确处理中断开始与结束状态。但常见问题在于：中断结束后，部分设备未能正确重新激活音频会话，或未及时重启录音，导致录音丢失。如何确保在中断恢复后无缝继续录音，并兼容不同iOS版本的音频会话行为，成为稳定实现后台录音的关键挑战。

Answer 1

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在 iOS 开发中处理录音中断需要正确处理音频会话中断通知，并在中断结束后重新激活会话和录音。以下是完整的实现方案：

1. 设置音频会话类别

import AVFoundation


func setupAudioSession() {
    do {
        let audioSession = AVAudioSession.sharedInstance()
        try audioSession.setCategory(.playAndRecord, mode: .default, options: [.defaultToSpeaker, .allowBluetooth])
        try audioSession.setActive(true)
    } catch {
        print("设置音频会话失败: \(error.localizedDescription)")
    }
}

2. 注册中断通知

class AudioRecorderManager: NSObject {
    private var audioRecorder: AVAudioRecorder?
    private var isInterrupted = false
    private var shouldResume = false
    
    override init() {
        super.init()
        setupNotifications()
    }
    
    private func setupNotifications() {
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(handleAudioSessionInterruption(_:)),
            name: AVAudioSession.interruptionNotification,
            object: nil
        )
        
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(handleAppWillResignActive),
            name: UIApplication.willResignActiveNotification,
            object: nil
        )
        
        NotificationCenter.default.addObserver(
            self,
            selector: #selector(handleAppDidBecomeActive),
            name: UIApplication.didBecomeActiveNotification,
            object: nil
        )
    }
}

3. 处理音频中断的核心逻辑

extension AudioRecorderManager {
    @objc private func handleAudioSessionInterruption(_ notification: Notification) {
        guard let userInfo = notification.userInfo,
              let interruptionTypeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
              let interruptionType = AVAudioSession.InterruptionType(rawValue: interruptionTypeValue) else {
            return
        }
        
        switch interruptionType {
        case .began:
            // 中断开始
            handleInterruptionBegan()
        case .ended:
            // 中断结束
            guard let optionsValue = userInfo[AVAudioSessionInterruptionOptionKey] as? UInt else { return }
            let options = AVAudioSession.InterruptionOptions(rawValue: optionsValue)
            handleInterruptionEnded(shouldResume: options.contains(.shouldResume))
        @unknown default:
            break
        }
    }
    
    private func handleInterruptionBegan() {
        isInterrupted = true
        
        // 暂停录音但不释放资源
        audioRecorder?.pause()
        
        // 保存当前录音状态
        shouldResume = audioRecorder?.isRecording ?? false
        
        print("录音被中断")
    }
    
    private func handleInterruptionEnded(shouldResume: Bool) {
        isInterrupted = false
        
        // 重新激活音频会话
        do {
            let audioSession = AVAudioSession.sharedInstance()
            try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
            
            // 如果需要恢复且之前正在录音
            if shouldResume && self.shouldResume {
                resumeRecording()
            }
            
        } catch {
            print("重新激活音频会话失败: \(error.localizedDescription)")
            // 可以在这里添加重试逻辑
            attemptToRecoverFromError()
        }
    }
}

4. 恢复录音的实现

extension AudioRecorderManager {
    private func resumeRecording() {
        guard let recorder = audioRecorder else { return }
        
        // 检查录音器状态
        if recorder.isRecording {
            return // 已经在录音
        }
        
        do {
            // iOS 16+ 兼容性处理
            if #available(iOS 16.0, *) {
                // 确保音频会话已激活
                let audioSession = AVAudioSession.sharedInstance()
                if !audioSession.isOtherAudioPlaying {
                    try audioSession.setActive(true)
                }
            }
            
            // 恢复录音
            recorder.record()
            print("录音已恢复")
            
        } catch {
            print("恢复录音失败: \(error.localizedDescription)")
            // 失败后尝试重新创建录音器
            recreateRecorderAfterInterruption()
        }
    }
    
    private func recreateRecorderAfterInterruption() {
        guard let currentRecorder = audioRecorder,
              let url = currentRecorder.url else { return }
        
        let settings = currentRecorder.settings
        let currentTime = currentRecorder.currentTime
        
        do {
            // 创建新的录音器实例
            let newRecorder = try AVAudioRecorder(url: url, settings: settings)
            newRecorder.delegate = self
            newRecorder.isMeteringEnabled = true
            
            if newRecorder.prepareToRecord() {
                audioRecorder = newRecorder
                
                // 从上次中断的位置继续录音
                if newRecorder.record(atTime: currentTime) {
                    print("录音器重新创建并恢复成功")
                }
            }
        } catch {
            print("重新创建录音器失败: \(error.localizedDescription)")
        }
    }
}

5. 应用前后台状态处理

extension AudioRecorderManager {
    @objc private func handleAppWillResignActive() {
        // 应用进入后台前的处理
        if audioRecorder?.isRecording == true {
            shouldResume = true
        }
    }
    
    @objc private func handleAppDidBecomeActive() {
        // 应用回到前台后的检查
        if shouldResume && !isInterrupted {
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
                self.resumeRecording()
            }
        }
    }
    
    private func attemptToRecoverFromError() {
        // 错误恢复策略
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
            do {
                try AVAudioSession.sharedInstance().setActive(true)
                self.resumeRecording()
            } catch {
                print("恢复尝试失败: \(error.localizedDescription)")
            }
        }
    }
}

6. 完整的录音管理器示例

class AudioRecorderManager: NSObject, AVAudioRecorderDelegate {
    static let shared = AudioRecorderManager()
    
    private var audioRecorder: AVAudioRecorder?
    private var isInterrupted = false
    private var shouldResume = false
    private var currentRecordingURL: URL?
    
    private override init() {
        super.init()
        setupNotifications()
        setupAudioSession()
    }
    
    func startRecording() throws {
        let audioSession = AVAudioSession.sharedInstance()
        try audioSession.setActive(true)
        
        let documentsPath = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
        let audioFilename = documentsPath.appendingPathComponent("recording-\(Date().timeIntervalSince1970).m4a")
        currentRecordingURL = audioFilename
        
        let settings: [String: Any] = [
            AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
            AVSampleRateKey: 44100.0,
            AVNumberOfChannelsKey: 1,
            AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
        ]
        
        audioRecorder = try AVAudioRecorder(url: audioFilename, settings: settings)
        audioRecorder?.delegate = self
        audioRecorder?.isMeteringEnabled = true
        audioRecorder?.prepareToRecord()
        
        if audioRecorder?.record() == true {
            print("开始录音")
        }
    }
    
    func stopRecording() {
        audioRecorder?.stop()
        shouldResume = false
    }
    
    // AVAudioRecorderDelegate
    func audioRecorderDidFinishRecording(_ recorder: AVAudioRecorder, successfully flag: Bool) {
        print("录音完成: \(flag)")
    }
    
    func audioRecorderEncodeErrorDidOccur(_ recorder: AVAudioRecorder, error: Error?) {
        if let error = error {
            print("录音编码错误: \(error.localizedDescription)")
        }
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
}

关键要点

1. 及时处理中断通知：在中断开始时暂停录音，保存状态
2. 正确重新激活会话：中断结束后重新激活音频会话
3. 兼容性处理：考虑不同 iOS 版本的音频会话行为差异
4. 错误恢复机制：提供重试逻辑来处理恢复失败的情况
5. 前后台状态协调：结合应用生命周期管理录音状态

这种实现方案能够有效处理来电、闹钟等系统事件导致的中断，确保录音能够在中断结束后无缝恢复。