implementing camera switch (front to back) upon button touch - ios

Question

I'm having trouble implementing "camera switch" upon button touch.
I'm still new to Swift and iOS developement, so most of the code I've currently implemented has been via tutorials.
I tried to implement the camera switch on my own.
However it's leading to this error:
Multiple audio/video AVCaptureInputs are not currently supported
I understand the error, but not sure how I would correctly implement the switch function within my code.
Here is the switch/flip function:
#IBAction func FlipCamera(_ sender: Any) {
captureSession.stopRunning()
cameraPreviewlayer?.removeFromSuperlayer()
//cameraPreviewlayer = nil
//self.captureSession = nil
setupCaptureSession()
if currentCamera! == backCamera{
//print(currentCamera)
currentCamera = frontCamera}
else {
currentCamera = backCamera}
setupCaptureSession()
setupInputOutput()
setupPreviewLayer()
startRunningCaptureSession()
}
Here is the class in its entirety:
class CameraViewController :UIViewController {
func applyRoundCorner(_ object: AnyObject){
object.layer.cornerRadius = (object.frame.size.width)/2
object.layer.masksToBounds = true
}
#IBOutlet weak var cameraButton: UIButton!
#IBOutlet weak var imagePreview: UIImageView!
#IBAction func Library(_ sender: Any) {
}
#IBAction func FlipCamera(_ sender: Any) {
captureSession.stopRunning()
cameraPreviewlayer?.removeFromSuperlayer()
//cameraPreviewlayer = nil
//self.captureSession = nil
setupCaptureSession()
if currentCamera! == backCamera{
//print(currentCamera)
currentCamera = frontCamera}
else {
currentCamera = backCamera}
setupCaptureSession()
setupInputOutput()
setupPreviewLayer()
startRunningCaptureSession()
}
var captureSession = AVCaptureSession()
var backCamera: AVCaptureDevice?
var frontCamera: AVCaptureDevice?
var currentCamera: AVCaptureDevice?
var cameraPreviewlayer: AVCaptureVideoPreviewLayer?
var photoOutput: AVCapturePhotoOutput?
var image: UIImage?
override func viewDidLoad() {
super.viewDidLoad()
self.applyRoundCorner(cameraButton)
setupCaptureSession()
setupInputOutput()
setupPreviewLayer()
startRunningCaptureSession()
}
func setupCaptureSession(){
captureSession.sessionPreset = AVCaptureSession.Preset.photo // Why exclamation point?
let availableDevice = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: .video, position: .unspecified)
let devices = availableDevice.devices //back or front
for device in devices {
if device.position == AVCaptureDevice.Position.back{
backCamera = device
}else if device.position == AVCaptureDevice.Position.front{
frontCamera = device
}
}
currentCamera = backCamera
}
func setupInputOutput(){
do {
let captureDeviceInput = try AVCaptureDeviceInput(device: currentCamera!)
captureSession.addInput(captureDeviceInput)
photoOutput = AVCapturePhotoOutput()
photoOutput?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format:[AVVideoCodecKey:AVVideoCodecType.jpeg])], completionHandler: nil)
captureSession.addOutput(photoOutput!)
}
catch{
print(error)
}
}
func setupPreviewLayer(){
cameraPreviewlayer = AVCaptureVideoPreviewLayer(session: captureSession)
cameraPreviewlayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
cameraPreviewlayer?.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
cameraPreviewlayer?.frame = self.imagePreview.frame
self.view.layer.insertSublayer(cameraPreviewlayer!, at: 0)
}
func startRunningCaptureSession(){
captureSession.startRunning()
}
#IBAction func TakePhoto(_ sender: Any) {
let settings = AVCapturePhotoSettings()
photoOutput?.capturePhoto(with: settings, delegate: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
if segue.identifier == "showPhotoSegue"{
let previewVC = segue.destination as! PreviewViewController
previewVC.image = self.image
}
}
}
extension CameraViewController: AVCapturePhotoCaptureDelegate{
func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
if let imageData = photo.fileDataRepresentation(){
image = UIImage(data: imageData)
performSegue(withIdentifier:"showPhotoSegue", sender: nil) }
}
}