audio - 在 Swift 中录制音频

Question

有谁知道我在哪里可以找到有关如何在 Swift 应用程序中录制音频的信息？我一直在查看一些音频播放示例，但我似乎无法找到任何关于实现录音的内容。谢谢

Answer 1

在 Swift 3 中

• 添加框架 AVFoundation
• **在info.plist中添加键值

Key = Privacy - Microphone Usage Description and Value = For using microphone

(如果您不提供该值，应用程序将崩溃 - 说明您请求权限的原因)**

• 导入 AVFoundation & AVAudioRecorderDelegate, AVAudioPlayerDelegate

  import AVFoundation
  
   class RecordVC: UIViewController , AVAudioRecorderDelegate, AVAudioPlayerDelegate
  

• 创建用于录制音频和播放音频的按钮，以及用于显示录制时间的标签，并为 start_recording 和 play_recording 提供导出和 Action ，并声明一些我们稍后将使用的变量

  @IBOutlet var recordingTimeLabel: UILabel!
  @IBOutlet var record_btn_ref: UIButton!
  @IBOutlet var play_btn_ref: UIButton!
  
  var audioRecorder: AVAudioRecorder!
  var audioPlayer : AVAudioPlayer!
  var meterTimer:Timer!
  var isAudioRecordingGranted: Bool!
  var isRecording = false
  var isPlaying = false
  

• 在viewDidLoad中查看记录权限

  override func viewDidLoad() {
      super.viewDidLoad()
      check_record_permission()
  }
  
  func check_record_permission()
  {
      switch AVAudioSession.sharedInstance().recordPermission() {
      case AVAudioSessionRecordPermission.granted:
          isAudioRecordingGranted = true
          break
      case AVAudioSessionRecordPermission.denied:
          isAudioRecordingGranted = false
          break
      case AVAudioSessionRecordPermission.undetermined:
          AVAudioSession.sharedInstance().requestRecordPermission({ (allowed) in
                  if allowed {
                      self.isAudioRecordingGranted = true
                  } else {
                      self.isAudioRecordingGranted = false
                  }
          })
          break
      default:
          break
      }
  }
  

• 生成要将该录音保存为 myRecording.m4a 的路径

  func getDocumentsDirectory() -> URL
  {
      let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
      let documentsDirectory = paths[0]
      return documentsDirectory
  }
  
  func getFileUrl() -> URL
  {
      let filename = "myRecording.m4a"
      let filePath = getDocumentsDirectory().appendingPathComponent(filename)
  return filePath
  }
  

• 设置记录器

  func setup_recorder()
  {
      if isAudioRecordingGranted
      {
          let session = AVAudioSession.sharedInstance()
          do
          {
              try session.setCategory(AVAudioSessionCategoryPlayAndRecord, with: .defaultToSpeaker)
              try session.setActive(true)
              let settings = [
                  AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
                  AVSampleRateKey: 44100,
                  AVNumberOfChannelsKey: 2,
                  AVEncoderAudioQualityKey:AVAudioQuality.high.rawValue
              ]
              audioRecorder = try AVAudioRecorder(url: getFileUrl(), settings: settings)
              audioRecorder.delegate = self
              audioRecorder.isMeteringEnabled = true
              audioRecorder.prepareToRecord()
          }
          catch let error {
              display_alert(msg_title: "Error", msg_desc: error.localizedDescription, action_title: "OK")
          }
      }
      else
      {
          display_alert(msg_title: "Error", msg_desc: "Don't have access to use your microphone.", action_title: "OK")
      }
  }
  

• 按下 start_recording 按钮开始录音并使用 updateAudioMeter 显示秒数，如果开始录音则结束录音

  @IBAction func start_recording(_ sender: UIButton)
  {
      if(isRecording)
      {
          finishAudioRecording(success: true)
          record_btn_ref.setTitle("Record", for: .normal)
          play_btn_ref.isEnabled = true
          isRecording = false
      }
      else
      {
          setup_recorder()
  
          audioRecorder.record()
          meterTimer = Timer.scheduledTimer(timeInterval: 0.1, target:self, selector:#selector(self.updateAudioMeter(timer:)), userInfo:nil, repeats:true)
          record_btn_ref.setTitle("Stop", for: .normal)
          play_btn_ref.isEnabled = false
          isRecording = true
      }
  }
  
  func updateAudioMeter(timer: Timer)
  {
      if audioRecorder.isRecording
      {
          let hr = Int((audioRecorder.currentTime / 60) / 60)
          let min = Int(audioRecorder.currentTime / 60)
          let sec = Int(audioRecorder.currentTime.truncatingRemainder(dividingBy: 60))
          let totalTimeString = String(format: "%02d:%02d:%02d", hr, min, sec)
          recordingTimeLabel.text = totalTimeString
          audioRecorder.updateMeters()
      }
  }
  
  func finishAudioRecording(success: Bool)
  {
      if success
      {
          audioRecorder.stop()
          audioRecorder = nil
          meterTimer.invalidate()
          print("recorded successfully.")
      }
      else
      {
          display_alert(msg_title: "Error", msg_desc: "Recording failed.", action_title: "OK")
      }
  }
  

• 播放录音

  func prepare_play()
  {
      do
      {
          audioPlayer = try AVAudioPlayer(contentsOf: getFileUrl())
          audioPlayer.delegate = self
          audioPlayer.prepareToPlay()
      }
      catch{
          print("Error")
      }
  }
  
  @IBAction func play_recording(_ sender: Any)
  {
      if(isPlaying)
      {
          audioPlayer.stop()
          record_btn_ref.isEnabled = true
          play_btn_ref.setTitle("Play", for: .normal)
          isPlaying = false
      }
      else
      {
          if FileManager.default.fileExists(atPath: getFileUrl().path)
          {
              record_btn_ref.isEnabled = false
              play_btn_ref.setTitle("pause", for: .normal)
              prepare_play()
              audioPlayer.play()
              isPlaying = true
          }
          else
          {
              display_alert(msg_title: "Error", msg_desc: "Audio file is missing.", action_title: "OK")
          }
      }
  }
  

• 录制完成后启用播放按钮 & 播放完成后启用录制按钮

  func audioRecorderDidFinishRecording(_ recorder: AVAudioRecorder, successfully flag: Bool)
  {
      if !flag
      {
          finishAudioRecording(success: false)
      }
      play_btn_ref.isEnabled = true
  }
  
  func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool)
  {
      record_btn_ref.isEnabled = true
  }
  

• 显示警报的泛化函数

  func display_alert(msg_title : String , msg_desc : String ,action_title : String)
  {
      let ac = UIAlertController(title: msg_title, message: msg_desc, preferredStyle: .alert)
      ac.addAction(UIAlertAction(title: action_title, style: .default)
      {
          (result : UIAlertAction) -> Void in
      _ = self.navigationController?.popViewController(animated: true)
      })
      present(ac, animated: true)
  }