Strings manipulation in swift (Compatible with swift 4)

StringsManipulationDemo.swift

let constantString = "This is a single line string"

//now a multiline string
let quotation = """
  The White Rabbit put on his spectacles.  "Where shall I begin,
  please your Majesty?" he asked.

  "Begin at the beginning," the King said gravely, "and go on
  till you come to the end; then stop."
"""