How to restrict UITextField to take only numbers in Swift?

Question

I want the user to only enter numeric values in a UITextField. On iPhone we can show the numeric keyboard, but on iPad the user can switch to any keyboard.

Answer 1

Dead simple solution for Double numbers (keep it mind that this is not the best user-friendly solution), in your UITextFieldDelegate delegate:

func textField(_ textField: UITextField,
               shouldChangeCharactersIn range: NSRange,
               replacementString string: String) -> Bool {
        guard let currentString = textField.text as NSString? else {
            return false
        }
        let newString = currentString.replacingCharacters(in: range, with: string)
        return Double(newString) != nil
}