reloadData() from another viewController Swift - swift

Question

I have two viewControllers: the first one has a tableView in it and the second one has a textField with an action, if there is a specific text inserted in the textFiled, I want to call loadData1() function which has orderTable.reloadData() to reload the tableView from the logInviewController, but it returns nil when I call it.
tableViewController code :
import UIKit
import FirebaseFirestore
import Firebase
import FirebaseAuth
class orderTableViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate {
#IBOutlet var orderTable: UITableView!
var db: Firestore!
var firstName = [String]()
var lastName = [String]()
override func viewDidLoad() {
super.viewDidLoad()
orderTable.register(UINib(nibName: "Order1TableViewCell", bundle: nil) , forCellReuseIdentifier: "orderCell")
}
func loadData1() {
Firestore.firestore().collection("hola").getDocuments() { [self]
(querySnapshot, err) in
if let err = err
{
print("Error getting documents: \(err)");
}
else
{
for document in querySnapshot!.documents {
self.firstName.append(document.get("firstname") as? String ?? "")
self.lastName.append(document.get("lastname") as? String ?? "")
}
}
orderTable.reloadData() // from here i got Unexpectedly found nil while unwrapping an Optional value:
}
}
}
}
logInViewController code :
import UIKit
import Firebase
import FirebaseAuth
class logInViewController: UIViewController, UITextFieldDelegate {
#IBOutlet var userNameField: UITextField!
#IBOutlet var passwordField: UITextField!
#IBOutlet var logInButton: UIButton!
var db: Firestore!
var order: orderTableViewController!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func textfieldDidChange(_ sender: Any) {
print(userNameField?.text ?? "")
if userNameField.text == "v#v.com" {
let i = orderTableViewController()
i.loadData1()
}
}
}

Answer 1

Where you have let i = orderTableViewController(), you are not referencing your existing table view controller, but rather are creating a new one, except this time it is not instantiated in conjunction with the storyboard scene, and thus all of your #IBOutlet references will be nil. Attempts to reference those #IBOutlet references will fail.
To fix this, you should pass a reference for the first view controller to the second one, using a protocol rather than an explicit class name, and then the second view controller can call a method in the first. Thus:
Create class protocol, e.g. LoginViewControllerDelegate:
protocol LoginViewControllerDelegate: class { }
Give that protocol one method requirement, loadData1:
protocol LoginViewControllerDelegate: class {
func loadData1()
}
Make your first view controller conform to that protocol:
extension OrderTableViewController: LoginViewControllerDelegate {
func loadData1() {
... your implementation here ...
}
}
Create a property in the second view controller, that LoginViewController, for this delegate-protocol reference, e.g.:
weak var delegate: LoginViewControllerDelegate?
When first view controller instantiates second, set this delegate property (e.g. if doing segues, it would be in prepareForSegue):
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destination = segue.destination as? LoginViewController {
destination.delegate = self
}
}
The second view controller then would call delegate?.loadData1() rather than i.loadData1().

Answer 2

If you do what I understand then you can do this. But you should use delegate or closure callback to do that.
#IBAction func textfieldDidChange(_ sender: Any) {
print(userNameField?.text ?? "")
if userNameField.text == "v#v.com" {
if let i = order {
i.loadData1()
}
}
}
}