gistfile1.txt

extension String {
  
  init?(utf16chars:[UInt16]) {
    var str = ""
    var generator = utf16chars.generate()
    var utf16 : UTF16 = UTF16()
    var done = false
    while !done {
      let result = utf16.decode(&generator)
      switch result {
      case .EmptyInput:
        done = true
      case let .Result(val):
        str.append(Character(val))
      case .Error:
        return nil
      }
    }
    self = str
  }
  
  func escapeUTF16() -> String {
    return Array(utf16)
      .map { String(format: "%04x", $0) }
      .reduce("") { (string, character) -> String in
        return "\(string)\(character)"
    }
  }
  
  func unescapeUTF16() -> String? {
    var index = 0
    var encodedChars = [UInt16]()
    while index < characters.count {
      let range = startIndex.advancedBy(index)..<startIndex.advancedBy(index + 4)
      let encodedChar = String(substringWithRange(range))
      let intValue = UInt16(strtoul(encodedChar, nil, 16))
      encodedChars.append(intValue)
      index += 4
    }
    return String(utf16chars: encodedChars)
  }
}