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

Split the string by non-digit characters to an array of digits and the join them back to a string:

Swift 1:

let stringArray = origString.componentsSeparatedByCharactersInSet(
    NSCharacterSet.decimalDigitCharacterSet().invertedSet)
let newString = NSArray(array: stringArray).componentsJoinedByString("")

Swift 2:

let stringArray = origString.componentsSeparatedByCharactersInSet(
    NSCharacterSet.decimalDigitCharacterSet().invertedSet)
let newString = stringArray.joinWithSeparator("")

Swift 3 & 4:

let newString = origString
    .components(separatedBy:CharacterSet.decimalDigits.inverted)
    .joined()