public function switchDefaultActivity(string $appname):Renderer
    {
        $file = JL::open(FEnv::get("framework.config.core.apps.file"));
        foreach ($file as $one => $val) {
            if ($val->isdefault == "yes") {
                $val->isdefault = "no";
                $val->update = new \DateTime('UTC');
            }
            if ($val->name == $appname) {
                $val->update = new \DateTime();
                $val->isdefault = "yes";
            }
        }

        $file = json_encode($file, JSON_PRETTY_PRINT);
        JL::put(FEnv::get("framework.config.core.apps.file"), $file);
        return ((new Renderer())->jsonRenderer(array("code" => 200, "msg" => "OK")));
    }