<?php

// Method 1: simple foreach loop
$favorites = get_user_favorites();
if ( isset($favorites) && !empty($favorites) ) :
	foreach ( $favorites as $favorite ) :
		// You'll have access to the post ID in this foreach loop, so you can use WP functions like get_the_title($favorite);
	endforeach; 
endif;


/**
* Method 2: WP_Query Object
* Check if there are favorites before instantiating the WP_Query.
* Passing an empty array as an argument returns ALL posts.
* @see https://codex.wordpress.org/Class_Reference/WP_Query#Post_.26_Page_Parameters
*/
$favorites = get_user_favorites();
if ( $favorites ) : // This is important: if an empty array is passed into the WP_Query parameters, all posts will be returned
$favorites_query = new WP_Query(array(
	'post_type' => 'post', // If you have multiple post types, pass an array
	'posts_per_page' => -1,
	'ignore_sticky_posts' => true,
	'post__in' => $favorites
));
if ( $favorites_query->have_posts() ) : while ( $favorites_query->have_posts() ) : $favorites_query->the_post();
	// Treat this like any other WP loop
endwhile; endif; wp_reset_postdata();
else :
	// No Favorites
endif;