Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value after I try to reloadData() - swift

Question

I am creating an app that scans barcodes and adds the barcode value (and name and date but working on that later). After I scan the barcode, I call the add method which should add it to my tableview but I am hitting an error at my reloadData().
import UIKit
class FirstViewController: UIViewController {
#IBOutlet weak var tableView: UITableView!
var data: [Ticket] = []
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
data = createArray()
}
func createArray() -> [Ticket] {
let video1 = Ticket(number: "123456789", name: "First Name - Last Name", date: "May 18th, 2019, 7 am")
let video2 = Ticket(number: "123456789", name: "First Name - Last Name", date: "May 18th, 2019, 7 am")
return [video1, video2]
}
}
extension FirstViewController: UITableViewDataSource, UITableViewDelegate {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return data.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let ticket = data[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: "TicketCell") as! TicketCell
cell.setTicket(ticket: ticket)
return cell
}
func add (_ code: String)
{
let tic = Ticket(number: code, name: "First Name - LastName", date: "May 18th, 2019, 10 am")
print(tic.number1)
print(tic.name1)
print(tic.date1)
data.append(tic)
self.tableView.reloadData() // Error Occurs Here
}
}
This is where I'm calling the add method from a different controller. The String "code" is the barcode's value:
func found(code: String) {
FirstViewController().add(code)
viewDidLoad()
}

Answer 1

Each time you add a barcode using FirstViewController(), you are creating a new instance of FirstViewController, you can use delegation to update the original instance.
First create a protocol with your add method
protocol BarcodeScanDelegate: class {
func add(_ code: String)
}
Extend FirstViewController to inherit BarcodeScanDelegate and move the add method
extension FirstViewController: BarcodeScanDelegate {
func add (_ code: String) {
let tic = Ticket(number: code, name: "First Name - LastName", date: "May 18th, 2019, 10 am")
self.data.append(tic)
self.tableView.reloadData()
}
}
Within the 2nd (barcode scan) view controller create a variable that keeps a reference to the above delegate
class BarcodeScanViewController: UIViewController {
weak var delegate: BarcodeScanDelegate?
func addScannedBarcode() {
self.delegate?.add("BARCODE_HERE")
}
}
Now when you launch 2nd (barcode scan) view controller, assign its variable delegate to self
class FirstViewController: UIViewController {
#IBOutlet var tableView: UITableView!
...
#objc func launchBarcodeScanner() {
let viewController = BarcodeViewController()
// or use following if you are using storyboard
// let viewController = self.storyboard!.instantiateViewController(withIdentifier: "BarcodeVC") as! BarcodeViewController
viewController.delegate = self // <<<
self.present(viewController, animated: true)
}
}

Answer 2

You have the tableView in FirstViewController class in storyboard.
But in this method you are not appending a ticket to the existing array. You are creating new instance for FirstViewController. The tableview is in storyboard and you are creating this FirstViewController instance programmatically. So the IBOutlet will be nil. So it is crashing.
func found(code: String) {
FirstViewController().add(code)//new FirstViewController instance
viewDidLoad()
}
Instead of adding the code from another view controller, pass the code to the FirstViewController using custom delegate and reload the tableview.