How to terminate speech recognition when user stop speaking with swift 5 - ios

Question

I'm trying to make user speak and get what user says right. I read like 20 different articles about speech recognition and almost all is same. It keeps listening to user for like 1 minute or more. I want it to stop recognation when user stop speaking. I want to catch a word/few words that user says. Is there something limiting the time that user speak?
My code block :
func recordAndRecognizeSpeech(){
if recognitionTask != nil {
recognitionTask?.cancel()
recognitionTask = nil
}
let audioSession = AVAudioSession.sharedInstance()
do {
try audioSession.setCategory(.record, mode: .measurement, options: .duckOthers)
try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
} catch {
print("audioSession properties weren't set because of an error.")
}
recognitionRequest = SFSpeechAudioBufferRecognitionRequest()
let node = audioEngine.inputNode
guard let request = recognitionRequest else {
fatalError("Unable to create an SFSpeechAudioBufferRecognitionRequest object")
}
//request.shouldReportPartialResults = true
// Setting requiresOnDeviceRecognition to false would use the Apple Cloud for speech recognition.
if speechRecognizer?.supportsOnDeviceRecognition ?? false{
request.requiresOnDeviceRecognition = true
}
guard let myRecognizer = SFSpeechRecognizer() else {
// A recognizer is not supported for the current locale
return
}
if !myRecognizer.isAvailable {
// A recognizer is not available now
return
}
recognitionTask = speechRecognizer?.recognitionTask(with: request, resultHandler: { result, error in
if let result = result {
DispatchQueue.main.async {
let bestString = result.bestTranscription.formattedString
print(bestString)
}
} else if let error = error {
print(error)
self.audioEngine.stop()
node.removeTap(onBus: 0)
self.recognitionRequest = nil
self.recognitionTask = nil
self.speakButton.isEnabled = true
}
})
let recordingFormat = node.outputFormat(forBus: 0)
node.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat){buffer,_ in
self.recognitionRequest!.append(buffer)
}
audioEngine.prepare()
do {
try audioEngine.start()
} catch {
return print(error)
}
}

Answer 1

You can check the power of the sound input, and if it reach a minimum value, start a timer (like 3 seconds), and stop after the timer fire.
var recorder: AVAudioRecorder?
recorder.updateMeters()
let dB = recorder.averagePower(forChannel: 0)