Complete startRecording() function for Travel the World via Speech Recognition and FlyoverKit in Swift Part 2

startRecording.swift

func startRecording() {
        if recognitionTask != nil { //created when request kicked off by the recognizer. used to track progress of a transcription or cancel it
            recognitionTask?.cancel()
            recognitionTask = nil
        }
        let audioSession = AVAudioSession.sharedInstance()
        do {
            try audioSession.setCategory(AVAudioSession.Category(rawValue: convertFromAVAudioSessionCategory(AVAudioSession.Category.record)), mode: .default)
            try audioSession.setMode(AVAudioSession.Mode.measurement)
            try audioSession.setActive(true, options: .notifyOthersOnDeactivation)
        } catch {
            print("Failed to setup audio session")
        }
        
        recognitionRequest = SFSpeechAudioBufferRecognitionRequest() //read from buffer
        
        let inputNode = audioEngine.inputNode
        
        guard let recognitionRequest = recognitionRequest else {
            fatalError("Could not create request instance")
        }
        recognitionRequest.shouldReportPartialResults = true
        recognitionTask = speechRecognizer?.recognitionTask(with: recognitionRequest) {
            res, err in
            var isLast = false
            if res != nil { //res contains transcription of a chunk of audio, corresponding to a single word usually
                isLast = (res?.isFinal)!
            }
            
            if err != nil || isLast {
                self.audioEngine.stop()
                inputNode.removeTap(onBus: 0)
                
                self.recognitionRequest = nil
                self.recognitionTask = nil
                
                self.locButton.isEnabled = true
                let bestStr = res?.bestTranscription.formattedString
                var inDict = self.locDict.contains { $0.key == bestStr}
                
                if inDict {
                    self.placeLbl.text = bestStr
                    self.userInputLoc = self.locDict[bestStr!]!
                }
                else {
                    self.placeLbl.text = "can't find it in the dictionary"
                    self.userInputLoc = FlyoverAwesomePlace.centralParkNY
                }
                self.mapSetUp()
            }
            
        }
        let format = inputNode.outputFormat(forBus: 0)
        inputNode.installTap(onBus: 0, bufferSize: 1024, format: format) {
            buffer, _ in
            self.recognitionRequest?.append(buffer)
        }
        audioEngine.prepare()
        
        do {
            try audioEngine.start()
        } catch {
            print("Can't start the engine")
        }
    }