Adds a new shipping method that calculates shipping price based on quantity of products

custom-woocommerce-shipping.php

<?php
/*
Plugin Name: Shipping Price per Quantity Plugin
Plugin URI: http://itsgoran.com
Description: Adds a new shipping method that calculates shipping price based on quantity of products - made for Cider.
Version: 1.0.0
Author: Goran Jakovljevic
Author URI: http://itsgoran.com
*/

/**
 * Check if WooCommerce is active
 */
if ( in_array( 'woocommerce/woocommerce.php', apply_filters( 'active_plugins', get_option( 'active_plugins' ) ) ) ) {

	function cider_shipping_method_init() {
		if ( ! class_exists( 'Cider_Shipping_Method' ) ) {
			class Cider_Shipping_Method extends WC_Shipping_Method {
				/**
				 * Constructor for your shipping class
				 *
				 * @access public
				 * @return void
				 */
				public function __construct() {
					$this->id                 = 'cider_shipping_method'; // Id for your shipping method. Should be uunique.
					$this->method_title       = __( 'Shipping Price per Quantity' );  // Title shown in admin
					$this->method_description = __( 'Shipping Price per Quantity Method' ); // Description shown in admin
					$this->title              = "Per Quantity"; // This can be added as an setting but for this example its forced.

					$this->init();
				}

				/**
				 * Init your settings
				 *
				 * @access public
				 * @return void
				 */
				function init() {
					// Load the settings API
					$this->init_form_fields(); // This is part of the settings API. Override the method to add your own settings
					$this->init_settings(); // This is part of the settings API. Loads settings you previously init.

					$this->enabled = $this->get_option( 'enabled' );
					$this->shipping_costs = $this->get_option( 'shipping_costs' );
					// Save settings in admin if you have any defined
					add_action( 'woocommerce_update_options_shipping_' . $this->id, array( $this, 'process_admin_options' ) );
				}

				/**
				 * Initialise Gateway Settings Form Fields
				 */
				public function init_form_fields() {
					$this->form_fields = array(
						'enabled' => array(
							'title' 		=> __( 'Enable/Disable', 'woocommerce' ),
							'type' 			=> 'checkbox',
							'label' 		=> __( 'Enable Custom Cider Shipping', 'woocommerce' ),
							'default' 		=> 'no'
						),
						'shipping_costs' => array(
							'title' 		=> __( 'Define Shipping Costs', 'woocommerce' ),
							'type' 			=> 'text',
							'label' 		=> __( 'Define Shipping Costs', 'woocommerce' ),
							'description' 		=> 'First number is quantity, second number is price. Add comma between different quantities.'
						)
					);
				}

				/**
				 * Get items in package
				 * @param  array $package
				 * @return int
				 */
				public function get_package_item_qty( $package ) {
					$total_quantity = 0;
					foreach ( $package['contents'] as $item_id => $values ) {
						if ( $values['quantity'] > 0 && $values['data']->needs_shipping() ) {
							$total_quantity += $values['quantity'];
						}
					}
					return $total_quantity;
				}

				/**
				 * calculate_shipping function.
				 *
				 * @access public
				 * @param mixed $package
				 * @return void
				 */
				public function calculate_shipping( $package ) {
					$rate = array(
						'id' => $this->id,
						'label' => $this->title,
						'taxes' => ''
					);
					$quantity = $this->get_package_item_qty($package); // Get quantity

					$array = array(); // Still suck at variable naming.
					$newarray = array(); // Yet again
					$array = explode(",",$this->shipping_costs); // shipping costs setting field, need to split
					foreach ($array as $key => $value) {
					  $new = explode(" ",$value); // one more split to get quantity - price key/value
					  $newarray[$new[0]] = $new[1];
					}

					foreach ($newarray as $key => $value) {
					  if($quantity <= $key) {
					    $rate['cost'] = $value;
					    break;
					  }
					}

					// Register the rate
					$this->add_rate( $rate );
				}
			}
		}
	}

	add_action( 'woocommerce_shipping_init', 'cider_shipping_method_init' );

	function add_cider_shipping_method( $methods ) {
		$methods[] = 'Cider_Shipping_Method';
		return $methods;
	}

	add_filter( 'woocommerce_shipping_methods', 'add_cider_shipping_method' );
}

public function calculate_shipping($package = array())
I use this function like this above but, $package is shown empty how I fix it ,
I need to get $package['destination']['address']; but in my case destination key is showing

tell u one thing this all in my custom plguin