on edit input field provide default value if textfield get empty swift
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let textFieldString = textField.text, let range = Range(range, in: textFieldString) else {
return false
}
let newString = textFieldString.replacingCharacters(in: range, with: string)
if newString.isEmpty {
textField.text = "0"
return false
} else if textField.text == "0" {
textField.text = string
return false
}
return true
}