Type 'String!' has no member 'photo'

I am following a tutorial on Youtube about CoreML: Real Time Camera object detection with machine learning - Swift 4 by Mr. Brian

captureSession.sessionPreset = .photo

Type "String" has no member 'photo'.

dataOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "videoQueue"))

Cannot convert value of type 'ViewController' to expected argument type 'AVCaptureVideoDataOutputSampleBufferDelegate!'

import UIKit

import AVFoundation

import AVKit

import Vision



class ViewController: UIViewController,         AVCaptureAudioDataOutputSampleBufferDelegate {

    override func viewDidLoad() {

        super.viewDidLoad()



        // here is where we start up the camera

        let captureSession = AVCaptureSession()

        captureSession.sessionPreset = .photo



        guard let captureDevice =

            AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo) else { return }



        guard let input = try? AVCaptureDeviceInput(device:

            captureDevice) else { return }

        captureSession.addInput(input)



        captureSession.startRunning()



        let previewLayer = AVCaptureVideoPreviewLayer(session:

            captureSession)

        view.layer.addSublayer(previewLayer!)

        previewLayer!.frame = view.frame



        let dataOutput = AVCaptureVideoDataOutput()

        dataOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "videoQueue"))

        captureSession.addOutput(dataOutput)