URL Encoded String Swift

URLEncodedString.swift

import Foundation


struct URLEncodedString {
  
  private (set) var encodedString: String
  
  init(_ string: String) {
    self.encodedString = URLEncodedString.URLEncode(string)
  }
  
  // Based on Alamofire Parameter Encoding: https://github.com/Alamofire/Alamofire/blob/master/Source/ParameterEncoding.swift
  static func URLEncode(string: String) -> String {
    let generalDelimiters = ":#[]@ " // does not include "?" or "/" due to RFC 3986 - Section 3.4
    let subDelimiters = "!$&'()*+,;="
    
    let allowedCharacters = generalDelimiters + subDelimiters
    let customAllowedSet =  NSCharacterSet(charactersInString:allowedCharacters).invertedSet
    let escapedString = string.stringByAddingPercentEncodingWithAllowedCharacters(customAllowedSet)!
    
    return escapedString
  }
  
}

extension URLEncodedString: StringLiteralConvertible {
  var description: String {
    get {
      return encodedString
    }
  }
}

extension URLEncodedString: CustomStringConvertible {
  
  init(stringLiteral value: String) {
    self.init(value)
  }
  
  init(extendedGraphemeClusterLiteral value: String) {
    self.init(value)
  }
  
  init(unicodeScalarLiteral value: String) {
    self.init(value)
  }
  
}