How do I refresh "Post Last Modified Time", as long as comment is updated to Approve status?

Question

I read from another question and tried their code which is pasted below - Update post date on every new comment?

This code is working well, however it updates the time when people Insert Comment in the front-end. What I seek is to update the time when admin Approve Comment in the back-end.

I read in another question and tried to replace with the hook suggested, but with no success - Approve comment hook?

add_action('wp_insert_comment','update_post_time',99,2);
function update_post_time($comment_id, $comment_object) {
    // Get the post's ID
    $post_id = $comment_object->comment_post_ID;
    // Double check for post's ID, since this value is mandatory in wp_update_post()
    if ($post_id) {
        // Get the current time
        $time = current_time('mysql');
        // Form an array of data to be updated
        $post_data = array(
            'ID'           => $post_id, 
            'post_modified'   => $time, 
            'post_modified_gmt' =>  get_gmt_from_date( $time )
        );
        // Update the post
        wp_update_post( $post_data );
    }
}

Answer 1

It's easy, you can just use different hook to perform same action.

add_action( 'comment_approved_', 'update_post_time', 99, 2); // this will fire when comment is approved regardless of comment type 

Last underscore in action name is important comment_approved_ as normally after it goes comment-type if you need to hook to approval to specific comment types.

See https://core.trac.wordpress.org/browser/trunk/src/wp-includes/comment.php#L1748