Add a custom field to save latitude and longitude to the edit screen of the specific post type for WordPress.
$ composer require miya/custom-field-map
<?php
require_once( dirname( __FILE__ ) . '/vendor/autoload.php' );
$map = new \Miya\WP\Custom_Field\Map( 'latlng', 'Latitude and Longitude' );
$map->add( 'post' ); // Set post type to display meta box.