gistfile1.rb

xml.instruct!
xml.declare! :DOCTYPE, :plist, :PUBLIC, "-//Apple Computer//DTD PLIST 1.0//EN", "http://www.apple.com/DTDs/PropertyList-1.0.dtd"
xml.plist("version" => 1.0) do |plist|
  plist.dict do |dict|
    Things.find_in_batches do |things|
      things.each do |thing|
        dict.key thing.id
        dict.array do |array|
          array.string thing.name
          array.string thing.address
          array.integer thing.number_of_frogs
        end
      end
    end
  end
end