Finding out whether a string is numeric or not

Question

How can we check if a string is made up of numbers only. I am taking out a substring from a string and want to check if it is a numeric substring or not.

NSS         


        

Answer 1

Simple wrote the string extension:

extension String {
    var isNumeric: Bool {
        return self.rangeOfCharacter(from: CharacterSet.decimalDigits.inverted) == nil
    }
}