AVFundation by SwiftUI with Coordinator.

ContentView.swift

struct ErrorInfo: Error {
    var showError: Bool
    var message: String
}

struct ContentView: View {
    @State var errorInfo: ErrorInfo = ErrorInfo(showError: false, message: "")
    @State var onAppear: Bool = false
    var body: some View {
        ZStack {
            VideoView(showError: $errorInfo.showError, errorMessage: $errorInfo.message, onAppear: $onAppear)

                .alert(isPresented: $errorInfo.showError) { () -> Alert in
                    Alert(title: Text($errorInfo.message.wrappedValue))
            }
            Text("dddd")
        }
        .edgesIgnoringSafeArea(.all)

    }
}

VideoCoordinator.swift

final class VideoCoordinator: NSObject {
    var parent: VideoView
    let session: AVCaptureSession = AVCaptureSession()
    var previewLayer: AVCaptureVideoPreviewLayer?
    private var videoDataOutput: AVCaptureVideoDataOutput?
    private var videoDataOutputQueue: DispatchQueue?
    private var captureDevice: AVCaptureDevice?
    init(parent: VideoView) {
        self.parent = parent
    }

    func sessionStart() {
        if session.isRunning { return }
        print("session start")
        session.startRunning()
    }

    func stopSession() {
        if !session.isRunning { return }
        session.stopRunning()
    }

    /// - Tag: CreateCaptureSession
    func setupAVCaptureSession() {
        print(#function)
        session.sessionPreset = .photo
        if let availableDevice = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: .video, position: .back).devices.first {
            captureDevice = availableDevice
        }

        do {
            let captureDeviceInput = try AVCaptureDeviceInput(device: captureDevice!)
            session.addInput(captureDeviceInput)
        } catch let error {
            print(error.localizedDescription)
        }

        let previewLayer = AVCaptureVideoPreviewLayer(session: session)
        self.previewLayer = previewLayer

        let dataOutput = AVCaptureVideoDataOutput()
        dataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String:kCVPixelFormatType_32BGRA]

        if session.canAddOutput(dataOutput) {
            session.addOutput(dataOutput)
        }

        session.commitConfiguration()

        let queue = DispatchQueue(label: "FromF.github.com.AVFoundationSwiftUI.AVFoundation")
        dataOutput.setSampleBufferDelegate(self, queue: queue)
    }

    // Removes infrastructure for AVCapture as part of cleanup.
    fileprivate func teardownAVCapture() {
        if let previewLayer = self.previewLayer {
            previewLayer.removeFromSuperlayer()
            self.previewLayer = nil
        }
    }
}

extension VideoCoordinator: AVCaptureVideoDataOutputSampleBufferDelegate {
    func captureOutput(_ output: AVCaptureOutput, didDrop sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

    }
}

VideoView.swift

struct VideoView: UIViewControllerRepresentable {
    typealias UIViewControllerType = UIViewController
    typealias Coordinator = VideoCoordinator
    @Binding var showError: Bool
    @Binding var errorMessage: String
    @Binding var onAppear: Bool
    func makeUIViewController(context: Context) -> UIViewController {
        let viewController = UIViewController()
        context.coordinator.sessionStart()
        if let previewLayer = context.coordinator.previewLayer {
            viewController.view.layer.addSublayer(previewLayer)
            previewLayer.frame = viewController.view.layer.frame
            print("context.coordinator.previewLayer?.frame: make \(String(describing: context.coordinator.previewLayer?.frame))")
        }

        return viewController
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: Context) {
        context.coordinator.previewLayer?.frame = uiViewController.view.layer.frame
        print("context.coordinator.previewLayer?.frame: update \(String(describing: context.coordinator.previewLayer?.frame))")
    }
    func makeCoordinator() -> VideoCoordinator {
        let coordinator = VideoCoordinator(parent: self)
        coordinator.setupAVCaptureSession()
        return coordinator
    }

    static func dismantleUIView(_ uiView: UIView, coordinator: VideoCoordinator) {
        coordinator.stopSession()
        coordinator.teardownAVCapture()
    }
}