How to get sub category of sub category?

Question

I have to load parent category, sub category and its sub categories. As of now, I can able to load the parent and its sub category but I have no idea how to load its sub category.

Below is the code I have used in template file:

<ul class="clearfix backcolor designmenu">
          <div class="totalmobilelog">
            <div class="lo">
              <a href="" ><b class="clsml"><i class="fa fa-user-plus" aria-hidden="true"></i>Login</b></a>
            </div>
            <div class="si">
              <a href="" ><b class="clsml"><i class="fa fa-registered" aria-hidden="true"></i>Sign Up</b></a>
            </div>
          </div>
          <?php
          $categories = $block->getStoreCategories();
          foreach ($categories as $category):

          ?>
          <li><a href="<?php echo $category->getRequestPath();?>"><?php echo $category->getName(); ?></a>
          <ul>
            <?php
            $subCategories = $block->getCategoryById($category->getId());
            foreach ($subCategories->getChildrenCategories() as $subCategory):
            ?>

            <li><a href="<?php echo $subCategory->getRequestPath();?>"><?php echo $subCategory->getName(); ?></a>
          </li>

          <?php endforeach; ?>
        </ul>
        <?php endforeach; ?>
      </li>
  </ul>

Code in block file:

protected $_categoryHelper;
protected $categoryFactory;
protected $_catalogLayer;
protected $_categoryRepository;


public function __construct(
    \Magento\Catalog\Block\Product\Context $context,     
    \Magento\Catalog\Helper\Category $categoryHelper,        
    \Magento\Catalog\Model\CategoryRepository $categoryRepository,        

    array $data = []
) {

    $this->_categoryHelper = $categoryHelper;   
    $this->_categoryRepository = $categoryRepository;
    parent::__construct(
        $context,          
        $data
    );


}


public function getStoreCategories($sorted = false, $asCollection = false, $toLoad = true)
{
    return $this->_categoryHelper->getStoreCategories($sorted , $asCollection, $toLoad);
}

public function getCategoryById($categoryId) 
{
    return $this->_categoryRepository->get($categoryId);

}

Can anyone please help me to load sub categories of sub category?

Code Tried:

<ul class="clearfix backcolor designmenu">
          <div class="totalmobilelog">
            <div class="lo">
              <a href="" ><b class="clsml"><i class="fa fa-user-plus" aria-hidden="true"></i>Login</b></a>
            </div>
            <div class="si">
              <a href="" ><b class="clsml"><i class="fa fa-registered" aria-hidden="true"></i>Sign Up</b></a>
            </div>
          </div>
          <?php
          $categories = $block->getStoreCategories();
          foreach ($categories as $category):

          ?>
          <li><a href="<?php echo $category->getRequestPath();?>"><?php echo $category->getName(); ?></a>
          <ul>
            <?php
            $subCategories = $block->getCategoryById($category->getId());
            foreach ($subCategories->getChildrenCategories() as $subCategory):
              $grandChildrenCategories[] = $subCategory->getChildrenCategories();
            ?>
            <li><a href="<?php echo $subCategory->getRequestPath();?>"><?php echo $subCategory->getName(); ?></a>
              <?php>
              foreach ($grandChildrenCategories as $subsubCategory):

              ?>
              <ul>

                <li><a href=""><?php echo $subsubCategory->getName(); ?></a></li>
              </ul>
            <?php endforeach; ?>
          </li>


          <?php endforeach; ?>
        </ul>
        <?php endforeach; ?>
      </li>
  </ul>

Code used in phtm:

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

// @codingStandardsIgnoreFile

?>
<?php
/**
 * Top menu for store
 *
 * @var $block \Magento\Theme\Block\Html\Topmenu
 */
?>


    <link rel="stylesheet" type="text/css" href="<?php echo $block->getViewFileUrl('css/cart.css')?>">

  <?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

// @codingStandardsIgnoreFile

?>
<?php
/**
 * Top menu for store
 *
 * @var $block \Magento\Theme\Block\Html\Topmenu
 */
?>

<header class="headers">
  <div class="header-inrs">
    <div class="menu-container">
      <div class="menus contenedor-menu">
        <ul class="clearfix backcolor designmenu">
          <div class="totalmobilelog">
            <div class="lo">
              <a href="" ><b class="clsml"><i class="fa fa-user-plus" aria-hidden="true"></i>Login</b></a>
            </div>
            <div class="si">
              <a href="" ><b class="clsml"><i class="fa fa-registered" aria-hidden="true"></i>Sign Up</b></a>
            </div>
          </div>
          <?php
          $categories = $block->getStoreCategories();
          foreach ($categories as $category):

          ?>
          <li><a href="<?php echo $category->getRequestPath();?>"><?php echo $category->getName(); ?></a>
          <ul class="subc">
            <?php
            $subCategories = $block->getCategoryById($category->getId());
            foreach ($subCategories->getChildrenCategories() as $subCategory):
            ?>

            <li><a href="<?php echo $subCategory->getRequestPath();?>"><?php echo $subCategory->getName(); ?></a>
          </li>

          <?php endforeach; ?>
        </ul>
        <?php echo $block->getSubcategories($subCategories); ?>
        <?php endforeach; ?>
      </li>
  </ul>
</div>
</div>
</div>
</header>

Answer 1

1.Please add below method on your block class

 public function  getSubcategories($categories) {
    $array ='';
    if($categories->getChildrenCount()>0){
            $array= '<ul class="child">';
            foreach($categories->getChildrenCategories() as $category) {
            $array .= '<li>'.
            '<a href="' .$category->getRequestPath().'">' .
                  $category->getName() . "</a>\n";
            if($category->hasChildren()) {
                $children = $this->getCategoryById($category->getId());
                 $array .=  $this->getSubcategories($children);
                }
             $array .= '</li>';
            }

        $array .= '</ul>';
    }
    return $array;
}

2. in phtml file add below code

         <ul class="main-ul">
                <?php
                $categorys = $block->getStoreCategories(false,false,true);
                  foreach($categorys as $category){ ?>
                    <li><a href="<?php echo $category->getRequestPath();?>"><?php echo $category->getName(); ?>
            <?php if($category->hasChildren()) {
                     $subCategories = $block->getCategoryById($category->getId()); 
    echo $block->getSubcategories($subCategories); 
} ?>
    </a>
               </li>
          <?php } ?>
        </ul>