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

Swift 3 solution if need to verify that the string has only digits:

CharacterSet.decimalDigits.isSuperset(of: CharacterSet(charactersIn: myString))