How to restrict UITextField to take only numbers in Swift?

Question

I want the user to only enter numeric values in a UITextField. On iPhone we can show the numeric keyboard, but on iPad the user can switch to any keyboard.

Answer 1

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool

        {
            let textString = (textField.text! as NSString).replacingCharacters(in: range, with: string)

            if textField == self.phoneTextField  && string.characters.count > 0{
                let numberOnly = NSCharacterSet.decimalDigits
                let strValid = numberOnly.contains(UnicodeScalar.init(string)!)
                return strValid && textString.characters.count <= 10
            }
            return true
        }

in above code is working in swift 3
NSCharacterSet.decimalDigits
You are also use letters only
NSCharacterSet.Letters
and uppercase,Lowercaseand,alphanumerics,whitespaces is used same code or See the Link