Swift Unexpectedly found nil while unwrapping an optional value while trying to move up the layout

Question

I need to move up the layout when the keyboard appears and the textfield won't be shown because of the size of the keyboard. Therefore I created this:

    var activeField: UITextField!

in my ViewDidLoad:

 let center: NotificationCenter = NotificationCenter.default;
    center.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: UIResponder.keyboardWillShowNotification, object: nil)
    center.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: UIResponder.keyboardWillHideNotification, object: nil)

and here are the methods:

 func textFieldDidBeginEditing(_ textField: UITextField) {
    activeField = textField
}

func textFieldShouldReturn(textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return true

}


@objc func keyboardWillShow(notification: Notification) {
    let info: NSDictionary = notification.userInfo as! NSDictionary
    let keyboardSize =  (info[UIResponder.keyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue

    let keyboardY = self.view.frame.size.height - keyboardSize.height

    let editingTextFieldY: CGFloat = self.activeField.frame.origin.y
    if editingTextFieldY > keyboardY - 60 {

        UIView.animate(withDuration: 0.25) {
            self.view.frame = CGRect(x: 0, y: self.view.frame.origin.y - (editingTextFieldY - (keyboardY-60)), width: self.view.bounds.width, height: self.view.bounds.height)
        }
    }

}

@objc func keyboardWillHide(notification: Notification) {
    UIView.animate(withDuration: 0.25, animations: {
        self.view.frame = CGRect(x:0, y:0, width: self.view.bounds.width, height: self.view.bounds.height)
    }, completion: nil)
}

the error appears at this line:

        let editingTextFieldY: CGFloat = self.activeField.frame.origin.y

In the modern era, the only way to do this is the technique of: **use autolayout perfectly for your screen. have one constraint which shapes the overall screen from the bottom. very simply just animate that ONE CONSTRAINT. and you're done - it's that easy. autolayout does everything."** Full tutorial: https://stackoverflow.com/a/41808338/294884 — Fattie, Dec 16 '18 at 14:23
Why are you still manually showing and hiding the keyboard? If you're in a navigation view hierarchy, just set the `navigationItem.searchController` to an instance of `UISearchController` and let iOS do all the heavy lifting for you. — NRitH, Dec 16 '18 at 14:43

score 1 · Accepted Answer · edited Dec 16 '18 at 14:17

1

This textFieldDidBeginEditing isn't being called.

You need to set the delegate of the origin textfield in viewDidLoad

self.mainTexF.delegate = self

edited Dec 16 '18 at 14:17

Mahgolsadat Fathi

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answered Dec 16 '18 at 12:41

Shehata Gamal

98,760
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1

It is probably called but not before the initial keyboard notification. – Sulthan Dec 16 '18 at 12:44
@Sulthan yes , but answers are always a guess – Shehata Gamal Dec 16 '18 at 12:53

Swift Unexpectedly found nil while unwrapping an optional value while trying to move up the layout

1 Answers1