Using protocols with services in swift - ios

Question

I have implemented an Audio Capturing service in my swift project that is supposed to handle audio recording and translates it into text.
AudioCaptureService
class AudioCaptureService:
// EXLCUDED A BUNCH OF SETUP CODE
func record(textView: UITextView, microphoneButton: UIButton) {
if audioEngine.isRunning {
audioEngine.stop()
recognitionRequest?.endAudio()
microphoneButton.setImage(#imageLiteral(resourceName: "microphone-full-white").withRenderingMode(.alwaysOriginal), for: .normal)
print("stopped recording...")
} else if !audioEngine.isRunning, isRecordingEnabled{
startRecording(textView: textView)
print("start recording...")
microphoneButton.setImage(#imageLiteral(resourceName: "microphone-red").withRenderingMode(.alwaysOriginal), for: .normal)
}
}
fileprivate func startRecording(textView: UITextView) {
if recognitionTask != nil {
recognitionTask?.cancel()
recognitionTask = nil
}
let audioSession = AVAudioSession.sharedInstance()
do {
try audioSession.setCategory(AVAudioSessionCategoryRecord)
try audioSession.setMode(AVAudioSessionModeMeasurement)
try audioSession.setActive(true, with: .notifyOthersOnDeactivation)
} catch {
print("audioSession properties weren't set because of an error.")
}
recognitionRequest = SFSpeechAudioBufferRecognitionRequest()
let inputNode = audioEngine.inputNode
guard let recognitionRequest = recognitionRequest else {
fatalError("Unable to create an SFSpeechAudioBufferRecognitionRequest object")
}
recognitionRequest.shouldReportPartialResults = true
recognitionTask = speechRecognizer?.recognitionTask(with: recognitionRequest, resultHandler: { (result, error) in
var isFinal = false
if result != nil {
textView.text = result?.bestTranscription.formattedString
isFinal = (result?.isFinal)!
}
if error != nil || isFinal {
self.audioEngine.stop()
inputNode.removeTap(onBus: 0)
self.recognitionRequest = nil
self.recognitionTask = nil
//self.microphoneButton.isEnabled = true
}
})
let recordingFormat = inputNode.outputFormat(forBus: 0)
inputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer, when) in
self.recognitionRequest?.append(buffer)
}
audioEngine.prepare()
do {
try audioEngine.start()
} catch {
print("audioEngine couldn't start because of an error.")
}
textView.text = ""
}
}
ViewController
In a separate view controller, I have a microphone button that is supposed to trigger this recording functionality. When the user clicks the microphone button, the button should turn red to indicate its recording, and then the audio that the user inputs will display in the textview of that view controller:
class PreviewController: UIViewController {
var notesOpen = false
let audioCaptureService = AudioCaptureService()
let microphoneButton: UIButton = {
let button = UIButton(type: .system)
button.addTarget(self, action: #selector(handleRecord), for: .touchUpInside)
button.setImage(#imageLiteral(resourceName: "muted-white").withRenderingMode(.alwaysOriginal), for: .normal)
button.isEnabled = false
return button
}()
lazy var notesView: UITextView = {
let frame = CGRect(x: 0, y: 0, width: 0, height: 0)
let tv = UITextView()
tv.layer.cornerRadius = 8
tv.font = UIFont.boldSystemFont(ofSize: 12)
tv.backgroundColor = .white
tv.keyboardDismissMode = .onDrag
return tv
}()
//EXCLUDED SOME BASIC SETUP CODE
#objc func handleRecord() {
print("record button pressed")
toggleNotesView()
audioCaptureService.record(textView: notesView, microphoneButton: microphoneButton)
}
Issue
Right now my implementation works, but I'm suspicious that it could be improved. I don't think I should be worried about passing in the textView and microphone button into my AudioCaptureService? Ideally, I'd like to have these things separate without AudioCaptureService depending on having a textView and button passed to it to work.
I was reading about protocols and think this may be a solution, but I can't seem to wrap my head around how I would implement this.
I was thinking I could do something like :
protocol AudioCaptureServiceDelegate {
func record(textView: UITextView)
}
But then who would the PreviewController class be the delegate? Im just a bit confused on how to better implement my code and any suggestions would help.

Answer 1

KISS would say conform in UITextView, if its just an output delegate, see below. If you want to handle more in the delegate it should definitely go to into the PreviewViewController cause UITextView is only to display text.
Some would recommend it should go into some kind of controller since audio != View, that is up for debate. Controller would mean the thing that controls the PreviewViewController which then sets text on PreviewViewController to display every time the text changes. The recordButton then leads through PreviewViewControllers' delegate to the controller which then handles recording, maybe storing the recordings somewhere, etc.
All in all a ViewController which lets its parent controller handle recording and displays text and changes the recordButton depending on the state the parent controller sets on the ViewController.
// Variant 1
protocol AudioCaptureServiceOutputDelegate: class {
func audioCaptureServiceOutputDelegate(outputChanged: String)
}
extension UITextView: AudioCaptureServiceOutputDelegate {
func audioCaptureServiceOutputDelegate(outputChanged: String) {
self.text = outputChanged
}
}
// Variant 2
protocol AudioCaptureServiceOutputDelegate2: class {
var text: String! { get set }
}
extension UITextView: AudioCaptureServiceOutputDelegate2 {}
// Variant 3
protocol AudioCaptureServiceOutputDelegate3: class {
var audioCaptureServiceOutputText: String { get set }
}
extension UITextView: AudioCaptureServiceOutputDelegate3 {
var audioCaptureServiceOutputText: String {
get { return text }
set { text = newValue }
}
}
All three work just as good. Variant 2 is just a little bit worse since a Controller/ViewController implementing a variable with the random name text may be a little too generic.
A controller would probably prefer 1, since what should it return on get? It has maybe several recordings stored already.
Calling example
func record(outputDelegate: AudioCaptureServiceOutputDelegate, microphoneButton: UIButton) {
// ....
startRecording(outputDelegate: outputDelegate)
// ....
}
fileprivate func startRecording(outputDelegate: AudioCaptureServiceOutputDelegate) {
// ....
outputDelegate.audioCaptureServiceOutputDelegate(outputChanged: result?.bestTranscription.formattedString ?? "Error: result is nil.")
// ....
outputDelegate.audioCaptureServiceOutputDelegate(outputChanged: "")
}