Swift source code generator from https://www.reddit.com/dev/api#GET_api_v1_me_prefs

generate_preference_struct.rb

class PreferenceStruct

  def initialize(line)
    typeTable = {
      "boolean"=>"Bool",
      "an integer between"=>"Int",
      "a valid IETF language tag"=>"String",
      "subreddit name" => "String",
      "one of \\(`on`, `off`, `subreddit`\\)" => "PreferenceMediaType",
      "one of \\(`confidence`, `old`, `top`, `qa`, `controversial`, `new`\\)" => "PreferenceDefaultCommentSortType"
    }

    if line =~ /\"(.+?)\"\: (.+),$/
      @originalName = $1
      @originalType = $2
    end
    @name = @originalName.gsub(/_(.)/) {$1.upcase}
    typeTable.each_pair{|key, value|
      if @originalType =~ /#{key}/
        @type = value
        break
      end
    }
  end

  def generateDeclaration
    sprintf("    let %s:%s?\n", @name, @type)
  end

  def PreferenceStruct.generateDeclaration(array)
    array.map {|item| item.generateDeclaration }.join
  end

  def generateCodeToInitWithAllParametersForArgments
    sprintf("        #{@name}:#{@type}? = nil")
  end

  def generateCodeToInitWithAllParameters
    sprintf("    self.#{@name} = #{@name}\n")
  end

  def PreferenceStruct.generateCodeToInitWithAllParameters(array)
    buf = ""
    buf = buf + "    public init(\n"
    buf = buf + array.map {|item| item.generateCodeToInitWithAllParametersForArgments }.join(",\n") + "\n"
    buf = buf + ") {\n"
    buf = buf + array.map {|item| item.generateCodeToInitWithAllParameters }.join
    buf = buf + "    }\n"
  end

  def generateCodeToInitWithJSON
    buf = ""
    if (@type == "PreferenceMediaType" || @type == "PreferenceDefaultCommentSortType")
      buf = buf + sprintf("        if let temp = json[\"#{@originalName}\"] as? String { self.#{@name} = #{@type}(temp) }\n")
      buf = buf + sprintf("        else { self.#{@name} = nil }\n")
    else
      buf = buf + sprintf("        self.#{@name} = json[\"#{@originalName}\"] as? #{@type}\n")
    end
  end

  def PreferenceStruct.generateCodeToInitWithJSON(array)
    buf = ""
    buf = buf + "    public init(json:[String:AnyObject]) {\n"
    buf = buf + array.map{|item| item.generateCodeToInitWithJSON}.join
    buf = buf + "    }\n"
  end

  def generateCodeToGenerateJSON
    if (@type == "PreferenceMediaType" || @type == "PreferenceDefaultCommentSortType")
      sprintf("        if let temp = #{@name} { json[\"#{@originalName}\"] = temp.rawValue }\n")
    else
      sprintf("        if let temp = #{@name} { json[\"#{@originalName}\"] = temp }\n")
    end
  end

  def PreferenceStruct.generateCodeToGenerateJSON(array)
    buf = ""
    buf = buf + "    public func json() -> [String:AnyObject] {\n"
    buf = buf + "        var json:[String:AnyObject] = [:]\n"
    buf = buf + array.map {|item| item.generateCodeToGenerateJSON }.join
    buf = buf + "        return json\n"
    buf = buf + "    }\n"
  end

  def PreferenceStruct.generateSourceCode(data)
      array = data.each_line.map {|line| PreferenceStruct.new(line)}
      puts "public struct Preference {"
      puts PreferenceStruct.generateDeclaration(array)
      puts PreferenceStruct.generateCodeToGenerateJSON(array)
      puts PreferenceStruct.generateCodeToInitWithJSON(array)
      puts PreferenceStruct.generateCodeToInitWithAllParameters(array)
      puts "}"
  end
end

PreferenceStruct.generateSourceCode(<<"EOS"
\"beta\": boolean value,
\"clickgadget\": boolean value,
\"collapse_read_messages\": boolean value,
\"compress\": boolean value,
\"creddit_autorenew\": boolean value,
\"default_comment_sort\": one of (`confidence`, `old`, `top`, `qa`, `controversial`, `new`),
\"domain_details\": boolean value,
\"email_messages\": boolean value,
\"enable_default_themes\": boolean value,
\"hide_ads\": boolean value,
\"hide_downs\": boolean value,
\"hide_from_robots\": boolean value,
\"hide_locationbar\": boolean value,
\"hide_ups\": boolean value,
\"highlight_controversial\": boolean value,
\"highlight_new_comments\": boolean value,
\"ignore_suggested_sort\": boolean value,
\"label_nsfw\": boolean value,
\"lang\": a valid IETF language tag (underscore separated),
\"legacy_search\": boolean value,
\"mark_messages_read\": boolean value,
\"media\": one of (`on`, `off`, `subreddit`),
\"min_comment_score\": an integer between -100 and 100,
\"min_link_score\": an integer between -100 and 100,
\"monitor_mentions\": boolean value,
\"newwindow\": boolean value,
\"no_profanity\": boolean value,
\"num_comments\": an integer between 1 and 500,
\"numsites\": an integer between 1 and 100,
\"organic\": boolean value,
\"other_theme\": subreddit name,
\"over_18\": boolean value,
\"private_feeds\": boolean value,
\"public_votes\": boolean value,
\"research\": boolean value,
\"show_flair\": boolean value,
\"show_gold_expiration\": boolean value,
\"show_link_flair\": boolean value,
\"show_promote\": boolean value,
\"show_stylesheets\": boolean value,
\"show_trending\": boolean value,
\"store_visits\": boolean value,
\"theme_selector\": subreddit name,
\"threaded_messages\": boolean value,
\"threaded_modmail\": boolean value,
\"use_global_defaults\": boolean value,
EOS
)