Swift 4 バーコードリーダアプリのメタデータ取得について

Swiftでバーコードリーダーを作成しているのですが、
カメラの起動は問題ないのですが、メタデータが取得できません。
ビルドは成功しています。
原因お分かりになりますでしょうか。
よろしくお願いいたします。

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCapturePhotoCaptureDelegate {

// Connect as outlet
@IBOutlet weak var previewView: UIView!

// Make instance
var captureSession = AVCaptureSession()

// Make notification
let notification = NotificationCenter.default

// Status for privacy and in-output
var authStatus:AuthorizedStatus = .authorized
var inOutStatus:InputOutputStatus = .ready

// Authorization Status
enum AuthorizedStatus {
    case authorized
    case notAuthorized
    case failed
}
// InOut Status
enum InputOutputStatus {
    case ready
    case notReady
    case failed
}

let x: CGFloat = 0.1
let y: CGFloat = 0.4
let width: CGFloat = 0.8
let height: CGFloat = 0.2

override func viewDidLoad(){
    super.viewDidLoad()
    // interrupt if processing session
    guard !captureSession.isRunning else {
        return
    }
    // privacy authorization for camera
    cameraAuth()

    // Set InputOutput
    setupInputOutput()

    // Check camera is ready
    if (authStatus == .authorized)&&(inOutStatus == .ready) {
        // Set previewLayer
        setPreviewLayer()
        // Start session
        captureSession.startRunning()
    } else {
        // alert
        showAlert(appName: "Camera")
    }

}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    if (captureSession.isRunning == false) {
        captureSession.startRunning()
    }
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)

    if (captureSession.isRunning == true) {
        captureSession.stopRunning()
    }
}

func cameraAuth(){
    let status = AVCaptureDevice.authorizationStatus(for: AVMediaType.video)
    switch status {
    case .notDetermined:
        AVCaptureDevice.requestAccess(for: AVMediaType.video,
                                      completionHandler: { [unowned self] authorized in print("First Time", authorized.description)
                                        if authorized {
                                            self.authStatus = .authorized
                                        } else {
                                            self.authStatus = .notAuthorized
                                        }})
    case .restricted, .denied:
        authStatus = .notAuthorized
    case .authorized:
        authStatus = .authorized
    }
}

func setupInputOutput(){
    // Set resolution
    // captureSession.sessionPreset = AVCaptureSession.Preset.

    // Set input
    do {
        // Obtain devise
        let devise = AVCaptureDevice.default(
            AVCaptureDevice.DeviceType.builtInWideAngleCamera,
            for: AVMediaType.video,
            position: AVCaptureDevice.Position.back
        )

        // where to input
        let input = try AVCaptureDeviceInput(device: devise!)
        if captureSession.canAddInput(input){
            captureSession.addInput(input)
        } else {
            print("Failed to add input to session")
            return
        }
    } catch let err as NSError {
        print("Camera doesn't exist \(err)")
        return
    }

    // Set output
    let metadataOutput = AVCaptureMetadataOutput()
    if captureSession.canAddOutput(metadataOutput) {
        captureSession.addOutput(metadataOutput)
        metadataOutput.setMetadataObjectsDelegate((self as? AVCaptureMetadataOutputObjectsDelegate), queue: DispatchQueue.main)
        metadataOutput.metadataObjectTypes = [.ean13]
        metadataOutput.rectOfInterest = CGRect(x: y, y: 1 - x - width, width: height, height: width)
    } else {
        print("Failed to add output to session")
        return
    }
}

func setPreviewLayer(){
    // Make previewLayer
    let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    previewLayer.frame = view.layer.bounds
    previewLayer.videoGravity = AVLayerVideoGravity.resizeAspect

    // Add preview
    previewView.layer.addSublayer(previewLayer)

    // Add red-frame
//        let detectionArea = UIView()
//        detectionArea.frame = CGRect(x: view.frame.size.width * x, y: view.frame.size.height * y, width: view.frame.size.width * width, height: view.frame.size.height * height)
//        detectionArea.layer.borderColor = UIColor.red.cgColor
//        detectionArea.layer.borderWidth = 3
//        view.addSubview(detectionArea)
}

func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection){
    for metadata in metadataObjects as! [AVMetadataMachineReadableCodeObject] {
        // check whether it's barcode
        if metadata.type == AVMetadataObject.ObjectType.ean13 {
            if metadata.stringValue != nil {
                print(metadata.stringValue!)
            }
        }
        print("metadataOutput called")

        // metadata
        print(metadata.type)
        print(metadata.stringValue!)
    }
}

func showAlert(appName: String){
    let aTitle = "privacy authorization for " + appName
    let aMessage = "Please authorize by Setting>Privacy> " + appName
    let alert = UIAlertController(title: aTitle, message: aMessage, preferredStyle: .alert)

    // OK(nothing)
    alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))

    // Open Setting
    alert.addAction(UIAlertAction(title: "Open Setting", style: .default, handler: { action in UIApplication.shared.open(URL(string: UIApplication.openSettingsURLString)!, options: [:], completionHandler: nil)}))

    // Display alert
    self.present(alert, animated: false, completion: nil)
}

}