gistfile1.txt

import Cocoa
import AVFoundation

class ViewController: NSViewController, AVCaptureVideoDataOutputSampleBufferDelegate {
    private let session = AVCaptureSession()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.wantsLayer = true

        AVCaptureDevice.DiscoverySession(deviceTypes: [.externalUnknown], mediaType: .video, position: .unspecified).devices.forEach {
            do {
                let input = try AVCaptureDeviceInput(device: $0) // 他にもプラグインがある場合は適当に調整する
                if session.canAddInput(input) {
                    session.addInput(input)
                }
            } catch {
                print(error)
            }
        }

        let previewLayer = AVCaptureVideoPreviewLayer()
        previewLayer.autoresizingMask = [.layerWidthSizable, .layerHeightSizable]
        previewLayer.session = session
        if let layer = view.layer {
            previewLayer.frame = layer.bounds
            layer.addSublayer(previewLayer)
        }

        session.startRunning()
    }
}