put character count and character type limit for the textfield swift 4 - swift

Question

I would like to put a limit for textfield. Example: Max character count should be 6 and characters can be digits only. But i could not put these two controls in one function.
First func for count of the text:
func textFieldCharacterCountLimit(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let maxLength = 6
let currentString: NSString = txt_phone_no_verification_code.text! as NSString
let newString: NSString =
currentString.replacingCharacters(in: range, with: string) as NSString
return newString.length <= maxLength
}
Second func for type of the text:
func textFieldCharacterTypeLimit(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let allowedCharacters = CharacterSet.decimalDigits
let characterSet = CharacterSet(charactersIn: string)
return allowedCharacters.isSuperset(of: characterSet)
}
Beside this, it gives an error also. And textFieldCharacterCountLimit function does not work. I think i get an error because two functions effect same textfield with return. Thanks

Answer 1

Allowing only a specified set of characters to be entered into a given text field with specific range
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if string.count == 0 {
return true
}
let currentText = textField.text ?? ""
let prospectiveText = (currentText as NSString).replacingCharacters(in: range, with: string)
return prospectiveText.containsOnlyCharactersIn(matchCharacters: "0123456789") &&
prospectiveText.count <= 6
}
String extension with condition
extension String {
// Returns true if the string contains only characters found in matchCharacters.
func containsOnlyCharactersIn(matchCharacters: String) -> Bool {
let disallowedCharacterSet = NSCharacterSet(charactersIn: matchCharacters).inverted
return self.rangeOfCharacter(from: disallowedCharacterSet as CharacterSet) == nil
}
}
How to program an iOS text field that takes only numeric input with a maximum length
http://www.globalnerdy.com/2015/04/27/how-to-program-an-ios-text-field-that-takes-only-numeric-input-or-specific-characters-with-a-maximum-length/

Answer 2

You can't just make up delegate method names. You need to implement the proper method and do all of your needed checking in the one method.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let newString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
if newString.count > 6 {
return false
}
return newString.rangeOfCharacter(from: CharacterSet.decimalDigits.inverted) == nil
}