Pfthb

I was following a tutorial on how to capture a barcode scanner from an ipad camera and this is the code that was written. The tutorial was written in xcode 8 and I am using Xcode 10. I am getting an error that

"Value of optional type 'AVCaptureDevice?' must be unwrapped to a
value of type 'AVCaptureDevice'"

in the do try catch statement. Can someone please tell me the correct way to deal with the optional value in this situation? When I change the line to read "let input = try AVCaptureDeviceInput(device: captureDevice!)"
the app crashes.

import AVFoundation
import UIKit

class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate 
 var video = AVCaptureVideoPreviewLayer() //contains what the camera is pointing at

 override func viewDidLoad() 
 super.viewDidLoad()

 //creates session
 let session = AVCaptureSession()

 //define capture device
 let captureDevice = AVCaptureDevice.default(for: AVMediaType.video)

 do
 let input = try AVCaptureDeviceInput(device: captureDevice)//Error occurs here
 session.addInput(input) //input coming from camera
 
 catch
 print("Error")
 
 let output = AVCaptureMetadataOutput()
 session.addOutput(output)

 output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
 output.metadataObjectTypes = [AVMetadataObject.ObjectType.code93, AVMetadataObject.ObjectType.code39] //may need to change this based on barcode type
 video = AVCaptureVideoPreviewLayer(session: session)
 video.frame = view.layer.bounds
 view.layer.addSublayer(video)
 session.startRunning()

 

 override func didReceiveMemoryWarning() 
 super.didReceiveMemoryWarning()