How to switch camera with a button in Swift?

Question

I'm creating a view to take a photo and send it to a server. I made a button to switch the camera from the back camera to the front camera and vice-versa, but I'm not sure how to implement it. I've done my research but I'm still confused on how to implement it in my project because I'm new to iOS programming. Here are some of my codes:

Some of my AVFoundation variables

private var session: AVCaptureSession!
private var stillImageOutput: AVCapturePhotoOutput!
private var stillImageSettings: AVCapturePhotoSettings!
private var previewLayer: AVCaptureVideoPreviewLayer!

My setupCamera() function. I call this function on viewDidAppear() as well

func setupCamera() {
        shutterButton.isUserInteractionEnabled = false

        if self.session != nil {
            self.session.stopRunning()
        }

        session = AVCaptureSession()
        session.sessionPreset = .photo
        guard let setCam: AVCaptureDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back) else {return}

        if setCam.isFocusModeSupported(.continuousAutoFocus) && setCam.isFocusPointOfInterestSupported {
            do {
                try setCam.lockForConfiguration()
                let focusPoint = CGPoint(x: 0.5, y: 0.5)
                setCam.focusPointOfInterest = focusPoint
                setCam.focusMode = .continuousAutoFocus
                setCam.isSubjectAreaChangeMonitoringEnabled = true
                setCam.unlockForConfiguration()
            } catch let error {
                print(error.localizedDescription)
            }
        }

        AVCaptureDevice.requestAccess(for: AVMediaType.video) { response in
            if response {
                // Access Granted
            } else {
                // Access Denied
                let alert = KPMAlertController(title: "Sorry", message: "Mohon maaf, untuk melakukan pengambilan foto, anda harus memberi akses penggunaan kamera", icon: UIImage(named: "ic_info_big"))
                let okAct = KPMAlertAction(title: "OK", type: .regular, handler : {
                    // Open setting
                    UIApplication.shared.open(URL(string: UIApplication.openSettingsURLString)!)
                    self.navigationController?.popViewController(animated: true)
                })
                alert.addAction(okAct)
                self.present(alert, animated: true, completion: nil)
            }
        }

        do {
            let input: AVCaptureDeviceInput = try AVCaptureDeviceInput(device: setCam)

            if self.session.canAddInput(input) {
                self.session.addInput(input)
                self.stillImageOutput = AVCapturePhotoOutput()
                if self.session.canAddOutput(self.stillImageOutput) {
                    self.session.addOutput(self.stillImageOutput)

                    self.previewLayer = AVCaptureVideoPreviewLayer(session: self.session)
                    self.previewLayer.frame = self.cameraView.bounds
                    self.previewLayer.videoGravity = .resizeAspectFill
                    self.previewLayer.connection?.videoOrientation = .portrait

                    self.cameraView.layer.addSublayer(self.previewLayer)

                    self.shutterButton.isUserInteractionEnabled = true

                    self.session.startRunning()
                    self.backButton.superview?.bringSubviewToFront(self.backButton)

                    self.shutterButton.superview?.bringSubviewToFront(self.shutterButton)
                }
            }

            ProgressHUD.dismiss()
        } catch let error {
            print(error.localizedDescription)
            ProgressHUD.dismiss()
        }
    }

And I want to implement the switch function here

@IBAction func switchCameraAction(_ sender: Any) {
    // The code to implement switching camera functionalities
}

If you need more code feel free to ask me. Any help would be appreciated. Thank you.