@jonathan, Today I started learning about hooks because I did not understand your given code earlier today. Now I understand everything except the add_post_meta($post_id, '_thumbnail_id', $value); where does '_thumbnail_id' come from?
Im trying to get the same thing to work, but I have an image field thats outputs as an object for other reasons. How can I make this code work with an image object field?
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users