VisionKit Barcode Scanner Enabling Highlights Using Swift - arrays

Question

I am learning how to create a barcode scanner and would like to add highlighting (the yellow square that goes around the numbers when the camera recognizes it)
I believe I should use isHighlightingEnabled: true
But I am not sure what line to put it on in my code. Where should I be placing it and do I need to add anything to make it work?
import UIKit
import Vision
import AVFoundation
import SafariServices
#objc class CMWSTVisionReader: UIViewController {
// MARK: - Private Variables
var captureSession = AVCaptureSession()
#IBOutlet weak var cameraView: UIView!
#IBOutlet weak var barcodeResult: UILabel!
// TODO: Make VNDetectBarcodesRequest variable
lazy var detectBarcodeRequest = VNDetectBarcodesRequest { request, error in
guard error == nil else {
// self.showAlert(
// withTitle: "Barcode error",
// message: error?.localizedDescription ?? "error")
return
}
self.processClassification(request)
}
// MARK: - Override Functions
override func viewDidLoad() {
super.viewDidLoad()
checkPermissions()
setupCameraLiveView()
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
// TODO: Stop Session
captureSession.stopRunning()
}
}
extension CMWSTVisionReader {
// MARK: - Camera
private func checkPermissions() {
// TODO: Checking permissions
switch AVCaptureDevice.authorizationStatus(for: .video) {
// 1
case .notDetermined:
AVCaptureDevice.requestAccess(for: .video) { [self] granted in
if !granted {
showPermissionsAlert()
}
}
// 2
case .denied, .restricted:
showPermissionsAlert()
// 3
default:
return
}
}
private func setupCameraLiveView() {
// TODO: Setup captureSession
captureSession.sessionPreset = .hd1280x720
// TODO: Add input
// 1
let videoDevice = AVCaptureDevice
.default(.builtInWideAngleCamera, for: .video, position: .back)
// 2
guard
let device = videoDevice,
let videoDeviceInput = try? AVCaptureDeviceInput(device: device),
captureSession.canAddInput(videoDeviceInput)
else {
// 3
showAlert(
withTitle: "Cannot Find Camera",
message: "There seems to be a problem with the camera on your device.")
return
}
// 4
captureSession.addInput(videoDeviceInput)
// TODO: Add output
let captureOutput = AVCaptureVideoDataOutput()
// TODO: Set video sample rate
captureOutput.videoSettings =
[kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA)]
captureOutput.setSampleBufferDelegate(
self,
queue: DispatchQueue.global(qos: DispatchQoS.QoSClass.default))
captureSession.addOutput(captureOutput)
configurePreviewLayer()
// TODO: Run session
captureSession.startRunning()
}
// MARK: - Vision
func processClassification(_ request: VNRequest) {
// TODO: Main logic
// 1
guard let barcodes = request.results else { return }
DispatchQueue.main.async { [self] in
if captureSession.isRunning {
view.layer.sublayers?.removeSubrange(1...)
// 2
for barcode in barcodes {
guard
// TODO: Check for QR Code symbology and confidence score
let potentialQRCode = barcode as? VNBarcodeObservation,
potentialQRCode.confidence > 0.9
else { return }
// 3
observationHandler(payload: potentialQRCode.payloadStringValue)
}
}
}
}
// MARK: - Handler
func observationHandler(payload: String?) {
// TODO: Open it in Safari
// 1
barcodeResult.text = payload
// guard
// let payloadString = payload,
// let url = URL(string: payloadString),
// ["http", "https"].contains(url.scheme?.lowercased())
// else { return }
//
// // 2
// let config = SFSafariViewController.Configuration()
// config.entersReaderIfAvailable = true
//
// // 3
// let safariVC = SFSafariViewController(url: url, configuration: config)
// safariVC.delegate = self
// present(safariVC, animated: true)
}
}
// MARK: - AVCaptureDelegation
extension CMWSTVisionReader: AVCaptureVideoDataOutputSampleBufferDelegate {
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
// TODO: Live Vision
// 1
guard let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
return
}
// 2
let imageRequestHandler = VNImageRequestHandler(
cvPixelBuffer: pixelBuffer,
orientation: .right)
// 3
do {
try imageRequestHandler.perform([detectBarcodeRequest])
} catch {
print(error)
}
}
}
// MARK: - Helper
extension CMWSTVisionReader {
private func configurePreviewLayer() {
let cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
cameraPreviewLayer.videoGravity = .resizeAspectFill
cameraPreviewLayer.connection?.videoOrientation = .portrait
cameraPreviewLayer.frame = cameraView.frame
cameraView.layer.insertSublayer(cameraPreviewLayer, at: 0)
}
private func showAlert(withTitle title: String, message: String) {
DispatchQueue.main.async {
let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
alertController.addAction(UIAlertAction(title: "OK", style: .default))
self.present(alertController, animated: true)
}
}
private func showPermissionsAlert() {
showAlert(
withTitle: "Camera Permissions",
message: "Please open Settings and grant permission for this app to use your camera.")
}
}
// MARK: - SafariViewControllerDelegate
extension CMWSTVisionReader: SFSafariViewControllerDelegate {
func safariViewControllerDidFinish(_ controller: SFSafariViewController) {
captureSession.startRunning()
}
}