Why custom shipping method not showing in checkout in Woocommerce?

Watson

I 'm creating a custom shipping method for woocommerce. But it can be added to a specific area in the admin area and just fine adjustment settings. But it doesn't appear on the checkout page for some reason and I don't have any clue why. It should be really straight forward and I did that a few times before (pre 3.0)-but I just can't get it to work right now.
Main Class

abstract class Main_Shipping extends WC_Shipping_Method
{
abstract protected function register_shipping($methods);
abstract protected function addActions();
abstract protected function addFilters();

function init() 
{
    $this->instance_form_fields                     = include('setting/shipping-settings.php' );
    $this->title                                    = $this->get_option('title' );
    $this->tax_status                               = $this->get_option('tax_status');
    $this->shipping_price                           = $this->get_option('shipping_price');
    $this->enable_free_shipping                     = $this->get_option('enable_free_shipping');
    $this->free_shipping_total                      = $this->get_option('free_shipping_total');

    $this->init_settings(); 

    add_action( 'woocommerce_update_options_shipping_' . $this->id, array( $this, 'process_admin_options' ) );
}

public function calculate_shipping($package = array())
{
    global $woocommerce;
    $return_price = $this->shipping_price;
    if(!isset($return_price))
    {
       $return_price = 0;
    }
    $rate = array(
        'id'      => $this->id .'_'. $this->instance_id,
        'label'   => $this->title,
        'cost'    => $return_price,
       );
    $this->add_rate( $rate );
}

public function oaship_pickuppoint()
{ 
    ob_start();
    ?>
        <div>
            test
        </div>

    <?php
    $sContent = ob_get_clean();
    echo $sContent;
}
}

specific GLS carrier Class:

function addActions()
{     
    add_action('woocommerce_after_shipping_rate', array($this, 'check_choosen_shipping_method') );
}

function addFilters()
{
    add_filter('woocommerce_shipping_methods', array($this, 'register_shipping_method'));
}

function register_shipping($methods) 
{

    $methods['gls_shipping_pickuppoint'] = 'GLS_Shipping_Pickuppoint';

    return $methods;
}

function check_choosen_shipping_method($rate)
{

    $chosen_methods = WC()->session->get( 'chosen_shipping_methods' );
    $chosen_shipping = preg_replace('/[0-9]+/', '', $chosen_methods[0]);;
    if($chosen_shipping === 'gls_shipping_pickuppoint')
    {
        if ($rate->method_id == 'gls_shipping_pickuppoint') {
            $this->oaship_pickuppoint();
        }
    }
}
}

$oOAGlsPickupPoint = new GLS_Shipping_Pickuppoint();
$oOAGlsPickupPoint->addActions();
 $oOAGlsPickupPoint->addFilters();

anderson

You need to check Enable debug mode in WooCommerce/Settings/Shipping/Shipping options and then you will be able to see my custom shipping in the checkout page. Then you have to disable the option again and my shipping is still visible in the checkout page.
Also in your code, you have missed an important action to add custom shipping
add_action( 'woocommerce_shipping_init', 'tutsplus_shipping_method' );
tutsplus_shipping_method defines the class that extends the WC_Shipping_Method

For woocommerce shipping action woocommerce_shipping_init is the main action which includes all the shipping classes before getting instantiated.
On more thing your filter add_filter('woocommerce_shipping_methods', array($this, 'register_shipping_method')); points to a function which is not there, maybe it's mistyped and you wanted to point to your register_shipping function.