IAP: Custom tag %pr_acf_author% to use ACF "Author" Field.

Custom tag %pr_acf_author% for Image Attributes Pro to use ACF Author Field.

 /**
 * Custom tag %pr_acf_author% for Image Attributes Pro to use ACF Author Field.
 * 
 * @param $image_id (integer) The ID of the image that is being updated. 
 * @param $parent_post_id (integer) Post to which the image is attached (uploaded) to. 
 * @param $args (array) An array containing additional arguments.
 * 
 * @return (string) Author of the post / page / product as defined in ACF, if available. Empty string otherwise. 
 * 
 * @refer https://imageattributespro.com/codex/iaffpro_get_custom_attribute_tag_tagname/
 */
function iaffpro_get_custom_attribute_tag_pr_acf_author( $image_id, $parent_post_id, $args = array() ) {

	if ( $parent_post_id == 0 ) {
		return '';
	}

	// Return if ACF is not installed.
	if ( ! function_exists( 'get_field' ) ) {
		return '';
	}
	
	$author = get_field( 'author', $parent_post_id );
	$author_name = '';

	if ( $author ) {
		foreach ( $author as $post_ids ) {
			$author_name = $author_name . get_the_title( $post_ids ) . ' ';
		}
	}
	
	return trim( $author_name, " ," );
}