Subcache example

add_filter('swift_performance_cache_folder_prefix', function($prefix){
    if (isset($COOKIE['your-cookie'])){
        return 'approved';
    }

    return $prefix;
});

add_action('swift_performance_prebuild_cache_hit', function($permalink){
    $COOKIE['your-cookie'] = 'set';
    Swift_Performance::prebuild_cache_hit($permalink);
});