add active class in single post

function add_active_class_to_category_menu( $classes, $item ) {
    if ( is_single() ) {
        $current_category = jnews_get_primary_category( get_the_ID() );
        if ( $current_category ) {
            if ( $item->object_id == $current_category && $item->object == 'category' ) {
                $classes[] = 'current-menu-item';
            }
        }
    }
    return $classes;
}
add_filter( 'nav_menu_css_class', 'add_active_class_to_category_menu', 10, 2 );