Disable UITextField cursor movement after max input - ios

Question

I created a custom UITextField component for a fixed size input. TextField's width, font size, kerning and character count are all fixed. I can block user from entering more than 8 characters (see below shouldChangeCharactersIn method), however after the 8th character, cursor automatically moves to next position, which creates the following problem.
I want to show all the entered characters without decreasing their size. So
[ 1 2 3 4 5 6 7 8 ]
should be shown instead of
[ 2 3 4 5 6 7 8 | ]
I tried to put cursor just right of the 8th character, however this changes the all kerning and effects all of the other characters.
What is the correct way to handle this? How should I prevent the cursor movement, so that UITextField won't scroll right?
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let textFieldText = textField.text,
let rangeOfTextToReplace = Range(range, in: textFieldText),
!string.containsSpecialCharacters else {
return false
}
let substringToReplace = textFieldText[rangeOfTextToReplace]
let count = textFieldText.count - substringToReplace.count + string.count
return count <= 8
}

Answer 1

I solved the problem by changing the kern after the last character. So now, instead of jumping 40pt, cursor jumps only 1pt (or whatever you set on below method)
#objc private func textFieldDidChange() {
guard let text = textField.text else { return }
if text.count == Constant.deviceCodeCharacterCount {
let attributedString = NSMutableAttributedString(string: text)
attributedString.addAttribute(.kern, value: Constant.deviceCodeCharacterSpacing, range: NSRange(location: 0, length: text.count - 1))
attributedString.addAttribute(.kern, value: 1, range: NSRange(location: Constant.deviceCodeCharacterCount - 1, length: 1))
textField.attributedText = attributedString
}
}

Answer 2

try the following code:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if textField.text?.count ?? 0 <= 7{
if textField.text?.count ?? 0 == 7{
DispatchQueue.main.async {
textField.resignFirstResponder()
}
}
return true
}
textField.resignFirstResponder()
return false
}
set your customTextField's delegate to self in your viewController's viewDidLoad method, and confirm to UITextFieldDelegate protocol

Answer 3

What happen if you try this code?
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
{
if range.location < 8 {
return true
}
// return NO to not change text
return false
}