UiTextfield- First letter must be 0

Question

I am using phone number texfield, now i am using this format for texfield (#) ### ### ###, now issue is that i want first character 0 as compulsary, like this (0) 959 554 54

Answer 1

In shouldChangeCharactersIn method of UITextFieldDelegate,

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if let text = textField.text {
        let str = (text as NSString).replacingCharacters(in: range, with: string).replacingOccurrences(of: "(0)", with: "")
        if !str.isEmpty {
            textField.text = "(0)" + str
        } else {
            textField.text = nil
        }
    }
    return false
}

Append (0) to the newly created string, everytime the textField is edited.