Filter non-digits from string

Question

Using only swift code I cant figure out how to take \"(555) 555-5555\" and return only the numeric values and get \"5555555555\". I need to remove all the parentheses, whit

Answer 1

Here is @Tapani's Swift 2.0 answer as a handy String extension, (length property is not part of solution but I left it in example because it is also handy):

import Foundation

extension String {

    var length : Int {
        return self.characters.count
    }

    func digitsOnly() -> String{
        let stringArray = self.componentsSeparatedByCharactersInSet(
            NSCharacterSet.decimalDigitCharacterSet().invertedSet)
        let newString = stringArray.joinWithSeparator("")

        return newString
    }

}

Usage:

let phone = "(123)-123 - 1234"
print(phone.digitsOnly())