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

Try this:

let string = "(555) 555-5555"
let digitString = string.filter { ("0"..."9").contains($0) }
print(digitString) // 5555555555

Putting in extension:

extension String
{
    var digitString: String { filter { ("0"..."9").contains($0) } }
}

print("(555) 555-5555".digitString) // 5555555555