SwiftUI QRCode Scanner

QRCodeScanner.swift

import SwiftUI
import AVFoundation

struct QRCodeScannerView: UIViewControllerRepresentable {
    
    var handleQRCode: (String) -> Void
    
    func makeUIViewController(context: Context) -> QRCodeScannerViewController {
        let viewController = QRCodeScannerViewController()
        viewController.handleQRCode = handleQRCode
        return viewController
    }
    
    func updateUIViewController(_ uiViewController: QRCodeScannerViewController, context: Context) { }
}

class QRCodeScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
    var handleQRCode: ((String) -> Void)?
    
    var captureSession: AVCaptureSession!
    var previewLayer: AVCaptureVideoPreviewLayer!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        captureSession = AVCaptureSession()
        
        guard let videoCaptureDevice = AVCaptureDevice.default(for: .video) else { return }
        let videoInput: AVCaptureDeviceInput
        
        do {
            videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
        } catch {
            return
        }

        if (captureSession.canAddInput(videoInput)) {
            captureSession.addInput(videoInput)
        } else {
            return
        }

        let metadataOutput = AVCaptureMetadataOutput()

        if (captureSession.canAddOutput(metadataOutput)) {
            captureSession.addOutput(metadataOutput)
            
            metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            metadataOutput.metadataObjectTypes = [.qr]
        } else {
            return
        }

        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        previewLayer.frame = view.layer.bounds
        previewLayer.videoGravity = .resizeAspectFill
        view.layer.addSublayer(previewLayer)
        
        captureSession.startRunning()
    }

    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        captureSession.stopRunning()

        if let metadataObject = metadataObjects.first {
            guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else { return }
            guard let stringValue = readableObject.stringValue else { return }
            AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
            handleQRCode?(stringValue)
        }
        
        dismiss(animated: true)
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        
        if (captureSession?.isRunning == true) {
            captureSession.stopRunning()
        }
    }
}