Abbreviated form of SpeechClient.live

speech_client_live.swift

import Combine
import ComposableArchitecture
import Speech

extension SpeechClient {
  static let live = SpeechClient(
    cancelTask: { id in
      .fireAndForget {
        dependencies[id]?.cancel()
        dependencies[id] = nil
      }
    },
    finishTask: { id in
      .fireAndForget {
        dependencies[id]?.finish()
        dependencies[id]?.subscriber.send(completion: .finished)
        dependencies[id] = nil
      }
    },
    recognitionTask: { id, request in
      Effect.run { subscriber in
        let cancellable = AnyCancellable {
          dependencies[id]?.cancel()
          dependencies[id] = nil
        }

        let speechRecognizer = // …
        let speechRecognizerDelegate = // …
        speechRecognizer.delegate = speechRecognizerDelegate

        let audioEngine = // …

        // …

        let inputNode = audioEngine.inputNode

        let recognitionTask = // …

        dependencies[id] = SpeechDependencies(
          audioEngine: audioEngine,
          inputNode: inputNode,
          recognitionTask: recognitionTask,
          speechRecognizer: speechRecognizer,
          speechRecognizerDelegate: speechRecognizerDelegate,
          subscriber: subscriber
        )

        // …

        return cancellable
      }
      .cancellable(id: id)
    },
    requestAuthorization: { /* … */ }
  )
}

private struct SpeechDependencies {
  let audioEngine: AVAudioEngine
  let inputNode: AVAudioInputNode
  let recognitionTask: SFSpeechRecognitionTask
  let speechRecognizer: SFSpeechRecognizer
  let speechRecognizerDelegate: SpeechRecognizerDelegate
  let subscriber: Effect<SpeechClient.Action, SpeechClient.Error>.Subscriber

  func finish() {
    self.audioEngine.stop()
    self.inputNode.removeTap(onBus: 0)
    self.recognitionTask.finish()
  }

  func cancel() {
    self.audioEngine.stop()
    self.inputNode.removeTap(onBus: 0)
    self.recognitionTask.cancel()
  }
}

private var dependencies: [AnyHashable: SpeechDependencies] = [:] // ⇐ This lil’ bub.

private class SpeechRecognizerDelegate: NSObject, SFSpeechRecognizerDelegate { /* … */ }