How to locate the line? unexpectedly found nil - ios

Question

When I try to run my app, I get the error stating:
fatal error: unexpectedly found nil while unwrapping an Optional
value.
Can anybody tell me if its a way to locate the line where the problem is?
Unfortunately, I don't get a red line where the simulator crashes.
I pasted in all of the code, but the problem must have to do with the alert function because it worked fine until I tried to implement that.
import UIKit
var list = ["Visa code: 1234", "Mastercard code: 4321"]
class notesVC: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var messageLabel: UILabel!
var userMessage = "Sample text"
var theUserText: UITextField?
#IBOutlet weak var tabelView: UITableView!
#IBAction func addItemButton(_ sender: Any) {
let alertController = UIAlertController(title:"title",
message: "message",
preferredStyle: .alert)
alertController.addTextField(configurationHandler: theUserTextFunc)
let okAction = UIAlertAction(title: "OK",
style: .default,
handler: self.okHandler)
let cancleAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
alertController.addAction(okAction)
alertController.addAction(cancleAction)
self.present(alertController, animated: true)
}
func theUserTextFunc(textField: UITextField){
theUserText = textField
}
func okHandler(alert: UIAlertAction!){
list.append((theUserText?.text)!)
}
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
return (list.count)
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "cell")
cell.textLabel?.text = list[indexPath.row]
return(cell)
}
// Swipe to delete an item
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == UITableViewCellEditingStyle.delete{
list.remove(at: indexPath.row)
tabelView.reloadData()
}
}
override func viewDidLoad() {
super.viewDidLoad()
messageLabel.text = userMessage
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func customInit(userMessage: String) {
self.userMessage = userMessage
}
}

Answer 1

I tried your code. It works flawless except that you missed to reload on table on OkHandler.
So I suspect issue would be with ur IBOutlet or IBAction connections. Check around that...
import UIKit
var list = ["Visa code: 1234", "Mastercard code: 4321"]
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource{
#IBOutlet weak var messageLabel: UILabel!
var userMessage = "Sample text"
var theUserText: UITextField?
#IBOutlet weak var tabelView: UITableView!
#IBAction func addItemButton(_ sender: Any) {
let alertController = UIAlertController(title:"title",
message: "message",
preferredStyle: .alert)
alertController.addTextField(configurationHandler: theUserTextFunc)
let okAction = UIAlertAction(title: "OK",
style: .default,
handler: self.okHandler)
let cancleAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)
alertController.addAction(okAction)
alertController.addAction(cancleAction)
self.present(alertController, animated: true)
}
func theUserTextFunc(textField: UITextField){
theUserText = textField
}
func okHandler(alert: UIAlertAction!){
list.append((theUserText?.text)!)
self.tabelView.reloadData()
}
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
return (list.count)
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "cell")
cell.textLabel?.text = list[indexPath.row]
return(cell)
}
// Swipe to delete an item
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == UITableViewCellEditingStyle.delete{
list.remove(at: indexPath.row)
tabelView.reloadData()
}
}
override func viewDidLoad() {
super.viewDidLoad()
messageLabel.text = userMessage
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func customInit(userMessage: String) {
self.userMessage = userMessage
}
}

Answer 2

Try changing your add code
alertController.addTextField(configurationHandler: theUserTextFunc)
to -
alertController.addTextField(configurationHandler: {(textField : UITextField!) -> Void in
textField.placeholder = "Search"
// Set other textfield values that you want
})