draw to CALayer directory.

gistfile1.txt

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {
    lazy var session: AVCaptureSession = .init()
    lazy var input: AVCaptureDeviceInput = try! AVCaptureDeviceInput(device: device)
    lazy var device: AVCaptureDevice = AVCaptureDevice.default(for: .video)!
    lazy var output: AVCaptureVideoDataOutput = .init()

    override func viewDidLoad() {
        super.viewDidLoad()
        session.addInput(input)
        session.addOutput(output)
        output.setSampleBufferDelegate(self, queue: .main)
        
        session.startRunning()
    }

    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        view.layer.contents = sampleBuffer.imageBuffer
    }
}