132 lines
4.3 KiB
Swift
132 lines
4.3 KiB
Swift
import AVFoundation
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/// The recording service that captures real audio from the device's microphone.
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///
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/// The service records into a temporary `.m4a` file through an `AVAudioRecorder`, and returns the file's location when the recording stops.
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/// The user's permission to record is requested before a recording starts and, on the platforms that require it, the shared audio session is
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/// configured for recording while the capture is in progress.
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@MainActor
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public final class AudioCapturing: Capturing {
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// MARK: Properties
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/// The recorder that captures the audio from the microphone into a temporary file.
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private var recorder: AVAudioRecorder?
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// MARK: Initializers
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/// Creates an audio recording service.
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public init() {}
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// MARK: Methods
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/// Starts a new audio recording from the microphone.
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///
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/// - Throws: ``AudioCapturingError/permissionNotGranted`` when the user denies the app access to the microphone,
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/// ``AudioCapturingError/captureNotStarted`` when the recorder fails to start, or any error thrown while configuring
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/// the audio session or creating the recorder.
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public func start() async throws {
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guard await AVAudioApplication.requestRecordPermission() else {
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throw AudioCapturingError.permissionNotGranted
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}
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#if os(iOS) || os(visionOS)
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let session = AVAudioSession.sharedInstance()
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try session.setCategory(.record, mode: .default)
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try session.setActive(true)
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#endif
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let recorder = try AVAudioRecorder(
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url: Constant.File.url,
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settings: Constant.Audio.settings
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)
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guard recorder.record() else {
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throw AudioCapturingError.captureNotStarted
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}
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self.recorder = recorder
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}
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/// Pauses the ongoing recording.
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///
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/// - Throws: ``AudioCapturingError/noOngoingRecording`` when no recording is in progress.
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public func pause() async throws {
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guard let recorder else {
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throw AudioCapturingError.noOngoingRecording
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}
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recorder.pause()
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}
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/// Resumes a paused recording.
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///
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/// - Throws: ``AudioCapturingError/noOngoingRecording`` when no recording is in progress, or
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/// ``AudioCapturingError/captureNotStarted`` when the recorder fails to resume.
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public func resume() async throws {
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guard let recorder else {
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throw AudioCapturingError.noOngoingRecording
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}
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guard recorder.record() else {
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throw AudioCapturingError.captureNotStarted
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}
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}
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/// Stops the recording, handing the temporary audio file over to the caller, which becomes responsible for deleting it.
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///
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/// - Returns: The location of the audio file captured since the recording started.
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/// - Throws: ``AudioCapturingError/noOngoingRecording`` when no recording is in progress.
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public func stop() async throws -> URL {
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guard let recorder else {
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throw AudioCapturingError.noOngoingRecording
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}
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recorder.stop()
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self.recorder = nil
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#if os(iOS) || os(visionOS)
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try? AVAudioSession.sharedInstance().setActive(false)
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#endif
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return Constant.File.url
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}
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}
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// MARK: - Errors
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/// The errors thrown by ``AudioCapturing``.
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public enum AudioCapturingError: Error {
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/// The recorder failed to start or resume the audio capture.
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case captureNotStarted
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/// No recording is in progress.
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case noOngoingRecording
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/// The user denied the app permission to record audio from the microphone.
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case permissionNotGranted
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}
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// MARK: - Constants
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/// The constant values used across the audio recording service.
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private enum Constant {
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/// The audio constants.
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enum Audio {
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/// The settings of the recorded audio: single-channel AAC at a 44.1 kHz sample rate, encoded in high quality.
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@MainActor
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static let settings: [String: Any] = [
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AVFormatIDKey: kAudioFormatMPEG4AAC,
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AVNumberOfChannelsKey: 1,
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AVSampleRateKey: 44_100.0,
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AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue,
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]
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}
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/// The file constants.
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enum File {
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/// The location of the temporary file the audio is captured into.
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static let url = FileManager.default.temporaryDirectory.appending(path: "recording.m4a")
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}
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}
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