String Range Extension

gistfile1.txt

extension String {

  subscript (i: Int) -> Character {
    return self[advance(self.startIndex, i)]
  }

  subscript (i: Int) -> String {
    return String(self[i] as Character)
  }

  subscript (r: Range<Int>) -> String {
    return substringWithRange(Range(start: advance(startIndex, r.startIndex), end: advance(startIndex, r.endIndex)))
  }
}

"abcde"[0] === "a"
"abcde"[0...2] === "abc"
"abcde"[2..<4] === "cd"