Force input into UITextField to uppercase

UITextFieldDelegate.m

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
       // Inspiration: http://stackoverflow.com/a/6265614 and http://stackoverflow.com/a/13388037
       //
       // Check if the added string contains lowercase characters.
       // If so, those characters are replaced by uppercase characters.
       //
       NSRange lowercaseCharRange = [string rangeOfCharacterFromSet:[NSCharacterSet lowercaseLetterCharacterSet]];

       if (lowercaseCharRange.location != NSNotFound) {

           if (textField.text.length == 0) {

               // Add first character -- and update Return button
               //
               // But this has the effect of losing the editing point
               // (only when trying to edit with lowercase characters),
               // because the text of the UITextField is modified,
               // which does not matter since the caret is at the end
               // of the (empty) text fiueld anyways.
               //
               textField.text = [textField.text stringByReplacingCharactersInRange:range withString:[string uppercaseString]];

           } else {

               // Replace range instead of whole string in order
               // not to lose input caret position -- but this will
               // not update the Return button, which is not necessary
               // here anyways
               //
               UITextPosition *beginning = textField.beginningOfDocument;
               UITextPosition *start = [textField positionFromPosition:beginning offset:range.location];
               UITextPosition *end = [textField positionFromPosition:start offset:range.length];
               UITextRange *textRange = [textField textRangeFromPosition:start toPosition:end];

               [textField replaceRange:textRange withText:[string uppercaseString]];
           }

           return NO;
      }

      return YES
}

SWIFT

@objc func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        guard
            let givenText = textField.text as NSString?,
            givenText.rangeOfCharacter(from: .lowercaseLetters).location != NSNotFound
        else { return true }
        
        let beginning = textField.beginningOfDocument
        
        if
            let start = textField.position(from: beginning, offset: range.location),
            let end = textField.position(from: start, offset: range.length),
            let textRange = textField.textRange(from: start, to: end)
        {
            textField.replace(textRange, withText: string.uppercased())
        }
        else
        {
            textField.text = givenText.replacingCharacters(in: range, with: string.uppercased())
        }
        
        return false
    }

This is almost good, but the first character will always be small