Unexpectedly found nil while unwrapping an Optional value

Question

juliusb OP

Created Dec ’22

Replies 1

Boosts 0

Participants 2

Hello, always when i try to run my app and press the button then i get this error. Can somebody help me? Thanks

import UIKit

class ViewController: UIViewController {

   
   
  override func viewDidLoad() {
    super.viewDidLoad()
    
  }

  @IBOutlet weak var calculatorLabel: UILabel!
   
  var isTypingNumber = false
   
  @IBAction func numberTapped(_ sender: UIButton) {
     
    let number = sender.currentTitle!
     
    if isTypingNumber {
      calculatorLabel.text = calculatorLabel.text! + number
    } else {
      calculatorLabel.text = number
      isTypingNumber = true
    }
     
  }
   
   
}

Bildschirmfoto 2022-12-04 um 19.22.39.png

Answered by Claude31 in 738347022

Welcome to the forum.

That's because currentTitle may be nil (depending on button state or because it has not yet been set).

You should write:

    let number = sender.currentTitle ?? (sender.titleLabel?.text ?? "0") // In last resort, consider it is "0"

Note: It is always very risky to unwrap an optional without checking for nil. Unless you are absolutely sure it is not nil (which is usually hard to be).

Boost

Answer 1

Claude31 OP

Dec ’22

Accepted Answer

Welcome to the forum.

That's because currentTitle may be nil (depending on button state or because it has not yet been set).

You should write:

    let number = sender.currentTitle ?? (sender.titleLabel?.text ?? "0") // In last resort, consider it is "0"

Note: It is always very risky to unwrap an optional without checking for nil. Unless you are absolutely sure it is not nil (which is usually hard to be).

1