swift String extension

swift String extension

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"