How to set the newly created user as author of a newly created post

When using a form to create both a user and post, you may choose to set the new user as the post author. Advanced Forms Pro handles user creation first and appends the newly created user ID to the AF()->submission array under the 'user' key. It is then available for use in subsequent hooks/filters as per the following example:

add_filter( 'af/form/editing/post_data', function ( $post_data, $form, $args ) {
  if ( $form['key'] === 'FORM_KEY' ) {
    $post_data['post_author'] = AF()->submission['user'];
  }
  
  return $post_data;
}, 10, 3 );