public function getMageShippingCountries($storeId = null)
    {
        return $this
            ->countryCollection
            ->loadByStore($this->storeManager->getStore($storeId))
            ->getColumnValues('country_id');
    }
public function getMageShippingCountries($storeId = null)
    {
        return $this
            ->countryCollection
            ->loadByStore($this->storeManager->getStore($storeId))
            ->getColumnValues('country_id');
    }
public function getMageShippingCountries ( $ storeId = null ) { return $ this -> countryCollection -> loadByStore ( $ this -> storeManager -> getStore ( $ storeId ) ) -> getColumnValues ( 'country_id' ) ; }
Retrieves magento's allowed shipping countries

@param null|string|int $storeId - store ID of which to get the ship countries

@return mixed
Retrieves magento s allowed shipping countries