Generate XML with Custom Post Type

DataFeed.php

<?php

/**
 * The admin-specific functionality of the plugin.
 *
 * @link       https://www.steadyrain.com
 * @since      1.0.0
 *
 * @package    The_Factory
 * @subpackage The_Factory/admin
 */

/**
 * The admin-specific functionality of the plugin.
 *
 * Defines the plugin name, version, and two examples hooks for how to
 * enqueue the admin-specific stylesheet and JavaScript.
 *
 * @package    The_Factory
 * @subpackage The_Factory/admin
 * @author     SteadyRain <info@steadyrain.com>
 */
class The_Factory_Data_Feed {

	/**
	 * The ID of this plugin.
	 *
	 * @since    1.0.0
	 * @access   private
	 * @var      string    $plugin_name    The ID of this plugin.
	 */
	private $plugin_name;

	/**
	 * The version of this plugin.
	 *
	 * @since    1.0.0
	 * @access   private
	 * @var      string    $version    The current version of this plugin.
	 */
	private $version;

	/**
	 * Initialize the class and set its properties.
	 *
	 * @since    1.0.0
	 * @param      string    $plugin_name       The name of this plugin.
	 * @param      string    $version    The version of this plugin.
	 */
	public function __construct( $plugin_name, $version ) {

		$this->plugin_name = $plugin_name;
		$this->version = $version;

    }

    public function generateDataXML($ID, $post)
    {
        $upload = wp_upload_dir();
        $upload_dir = $upload['basedir'];
        $upload_dir = $upload_dir . '/events';

        if ( ! file_exists( $upload_dir ) ) {
            wp_mkdir_p( $upload_dir );
        }

        $xml = new \SimpleXMLElement('<rss xmlns:g="http://base.google.com/ns/1.0" />', LIBXML_NOERROR, false, 'g', true);
        $xml->addAttribute('version', '2.0');

        $channel = $xml->addChild('channel');
        $channel->addChild('title', get_bloginfo('name'));
        $channel->addChild('link', get_bloginfo('url'));
        $channel->addChild('description', get_bloginfo('description'));

        $eventID = $post->ID;
        //die(var_dump(get_post_meta($eventID)));
        $eventDate = get_field( "date_of_event", $eventID );
        $postName = $post->post_name;
        $posttitle = $post->post_title;
        $abspath = get_site_url();
        $showInfo = $_POST['acf']['field_5f2241e2c0bf4'];
        $campaignShowInfo = $_POST['acf']['field_5f2458fc9d313'];
        $eventDate = $showInfo['field_5f224203c0bf5'];
        $campaignEventDate = $campaignShowInfo['field_5f2458fc9d315'];
        $doorsOpen = $showInfo['field_5f2242b5c0bf7'];
        $campaignDoorsOpen = $campaignShowInfo['field_5f2458fc9d317'];
        $tourName = $showInfo['field_5f22400c381dc'];
        $compaignTourName =  $campaignShowInfo['field_5f2458f49d30f'];
        $eventImage = intval($showInfo['field_5f245777ac9b5']);
        $campaignEventImage = intval($campaignShowInfo['field_5f2458f49d30f'];
        $image = wp_get_attachment_image_src($eventImage, 'full');
        $campaignImage = wp_get_attachment_image_src($campaignEventImage, 'full');

        $eventRow = $channel->addChild('item');
        $eventRow->addAttribute("id", $postName.'-'.$eventID);
        $eventRow->addChild("g:g:title", $posttitle);

        if (!empty($compaignTourName)) {
            $eventRow->addChild('g:g:tour', $compaignTourName);
        } else {
            $eventRow->addChild('g:g:tour', $tourName);
        }

        if (!empty($campaignEventDate)) {
            $eventRow->addChild('g:g:event', date('F j, Y', strtotime($campaignEventDate)));
        } else {
            $eventRow->addChild('g:g:event', date('F j, Y', strtotime($eventDate)));
        }

        if (!empty($campaignDoorsOpen)) {
            $eventRow->addChild('g:g:opens', $campaignDoorsOpen);
        } else {
            $eventRow->addChild('g:g:opens', $doorsOpen);
        }

        if ($campaignEventImage) {
            $eventRow->addChild('g:g:image', $campaignImage[0]);
        } else {
            $eventRow->addChild('g:g:image', $image[0]);
        }

        $file = trailingslashit( $upload_dir ) . 'events-data.xml';
        $open = fopen($file, 'w') or die ("File cannot be opened.");
        $dom = new \DOMDocument("1.0");
        $dom->preserveWhiteSpace = false;
        $dom->formatOutput = true;
        $dom->loadXML($xml->asXML());

        fwrite($open, $dom->saveXML());
        fclose($open);
    }    
}