Recording audio in Swift

Question

Does anyone know where I can find info on how to record audio in a Swift application? I\'ve been looking at some of the audio playback examples but I can\'t seem to be able

Answer 1

In addition to previous answers, I tried to make it work on Xcode 7.2 and I couldn't hear any sound after, neither when I sent the file via email. No warning or exception. So I changed settings to the following and stored as an .m4a file.

let recordSettings = [AVSampleRateKey : NSNumber(float: Float(44100.0)),
    AVFormatIDKey : NSNumber(int: Int32(kAudioFormatMPEG4AAC)),
    AVNumberOfChannelsKey : NSNumber(int: 1),
    AVEncoderAudioQualityKey : NSNumber(int: Int32(AVAudioQuality.Medium.rawValue))]

After that I could listen to sound. For saving the file, I added this on viewDidLoad to initialise the recorder:

let audioSession = AVAudioSession.sharedInstance()
    do {
        try audioSession.setCategory(AVAudioSessionCategoryPlayAndRecord)
        try audioRecorder = AVAudioRecorder(URL: self.directoryURL()!,
            settings: recordSettings)
        audioRecorder.prepareToRecord()
    } catch {
    }

And for creating the directory:

func directoryURL() -> NSURL? {
    let fileManager = NSFileManager.defaultManager()
    let urls = fileManager.URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
    let documentDirectory = urls[0] as NSURL
    let soundURL = documentDirectory.URLByAppendingPathComponent("sound.m4a")
    return soundURL 
}

I also add the actions used to start recording, stop, and play after

@IBAction func doRecordAction(sender: AnyObject) {
    if !audioRecorder.recording {
        let audioSession = AVAudioSession.sharedInstance()
        do {
            try audioSession.setActive(true)
            audioRecorder.record()
        } catch {
        }
   }
}
@IBAction func doStopRecordingAction(sender: AnyObject) {
    audioRecorder.stop()
    let audioSession = AVAudioSession.sharedInstance()

    do {
        try audioSession.setActive(false)
    } catch {
    }
}

@IBAction func doPlayAction(sender: AnyObject) {
    if (!audioRecorder.recording){
        do {
            try audioPlayer = AVAudioPlayer(contentsOfURL: audioRecorder.url)
            audioPlayer.play()
        } catch {
        }
    }
}

Answer 2

Here audio recorder with simple interface written on Swift 4.2 .

final class AudioRecorderImpl: NSObject {
  private let session = AVAudioSession.sharedInstance()
  private var player: AVAudioPlayer?
  private var recorder: AVAudioRecorder?
  private lazy var permissionGranted = false
  private lazy var isRecording = false
  private lazy var isPlaying = false
  private var fileURL: URL?
  private let settings = [
    AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
    AVSampleRateKey: 44100,
    AVNumberOfChannelsKey: 2,
    AVEncoderAudioQualityKey:AVAudioQuality.high.rawValue
  ]

  override init() {
    fileURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first?.appendingPathComponent("note.m4a")
  }

  func record(to url: URL?) {
    guard permissionGranted,
      let url = url ?? fileURL else { return }

    setupRecorder(url: url)

    if isRecording {
      stopRecording()
    }

    isRecording = true
    recorder?.record()
  }

  func stopRecording() {
    isRecording = false
    recorder?.stop()
    try? session.setActive(false)
  }

  func play(from url: URL?) {
    guard let url = url ?? fileURL else { return }

    setupPlayer(url: url)

    if isRecording {
      stopRecording()
    }

    if isPlaying {
      stopPlaying()
    }

    if FileManager.default.fileExists(atPath: url.path) {
      isPlaying = true
      setupPlayer(url: url)
      player?.play()
    }
  }

  func stopPlaying() {
    player?.stop()
  }

  func pause() {
    player?.pause()
  }

  func resume() {
    if player?.isPlaying == false {
      player?.play()
    }
  }

  func checkPermission(completion: ((Bool) -> Void)?) {
    func assignAndInvokeCallback(_ granted: Bool) {
      self.permissionGranted = granted
      completion?(granted)
    }

    switch session.recordPermission {
    case .granted:
      assignAndInvokeCallback(true)

    case .denied:
      assignAndInvokeCallback(false)

    case .undetermined:
      session.requestRecordPermission(assignAndInvokeCallback)
    }
  }
}

extension AudioRecorderImpl: AVAudioRecorderDelegate, AVAudioPlayerDelegate {

}

private extension AudioRecorderImpl {
  func setupRecorder(url: URL) {
    guard
      permissionGranted else { return }
    try? session.setCategory(.playback, mode: .default)
    try? session.setActive(true)
    let settings = [
      AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
      AVSampleRateKey: 44100,
      AVNumberOfChannelsKey: 2,
      AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
    ]
    recorder = try? AVAudioRecorder(url: url, settings: settings)
    recorder?.delegate = self
    recorder?.isMeteringEnabled = true
    recorder?.prepareToRecord()
  }

  func setupPlayer(url: URL) {
    player = try? AVAudioPlayer(contentsOf: url)
    player?.delegate = self
    player?.prepareToPlay()
  }
}