Codeigniter menu yamm bootstrap

mohon bantuan untuk membuat menu dengan tampilan seperti berikut: <a href='https://s11.postimg.org/abidgz11f/Screenshot_1.png '>https://s11.postimg.org/abidgz11f/Screenshot_1.png </a>

library : Menu_dropdown

class Menu_dropdown {

	protected $CI;
	public $menu;

	function __construct(){
		$this->CI =& get_instance();
	}

	// fungsi untuk mengambil menu
	function ambil_menu($type_menu,$parent=0){

		$kondisi=array(

			"menu_id"=>$type_menu,
			"menu_child_parent" => $parent,
			"aktif" => "Y"

			);

		//query ke database
		$this->CI->db->order_by("posisi","ASC");
		$query= $this->CI->db->get_where("menu_child",$kondisi);

		//cek apakah memiliki hasil
		if($query->num_rows()>0){
			$class=$parent==0?"nav navbar-nav":"dropdown-menu";
			$this->menu.="<ul class='$class'>";

			foreach ($query->result_array() as $menu) {
				//cek apakah menu sekarang mempunyai submenu atau tidak
				$cek=$this->CI->db->get_where("menu_child",array('menu_child_parent'=>$menu['menu_child_id'],'aktif'=>'Y','menu_id'=>$type_menu));

				//jika terdapat sub menu
				if($cek->num_rows()>0){

					$this->menu.= "<li class='dropdown yamm-fw'><a href='$menu[menu_child_url]' target='$menu[menu_child_target]' class='dropdown-toggle' data-hover='dropdown' data-toggle='dropdown'>$menu[menu_child_nama]</a>";
					//panggil ambil_menu() secara reqursive untuk mengambil sub-menu nya
					$this->ambil_menu($type_menu,$menu['menu_child_id']);
					$this->menu.= "</li>";

				}
				//jika tidak memiliki sub menu
				 else {
					$this->menu.= "<li><a href='$menu[menu_child_url]' target='$menu[menu_child_target]'>$menu[menu_child_nama]</a>";
					$this->menu.= "</li>";
				}

			}

			$this->menu.="</ul>";

			} else {
				//jika tidak ada hasil.
				//return;

			}
	}
}

Controller : AN_Controller

$this->load->library("menu_dropdown");
$this->menu_dropdown=$this->menu_dropdown->menu;

View

<div class="navbar-collapse collapse" id="mc-horizontal-menu-collapse">
<div class="nav-outer">
<?php

$menu_dropdown = new menu_dropdown;
$menu_dropdown->ambil_menu(1);
echo $menu_dropdown->menu;
?>
</div>