如何在Silex的自定义类中使用$app？

class CustomClass
{
    private $app;

    public function __construct($app)
    {
        $this->app = $app;
    }

    // 其他类方法可以使用$this->app访问$app对象
}

class CustomClass
{
    private $app;

    public function __construct($app)
    {
        $this->app = $app;
    }

    public function defineRoutes()
    {
        $this->app->get('/hello', function () {
            return 'Hello, World!';
        });
    }
}

$app = new Silex\Application();

$customClass = new CustomClass($app);
$customClass->defineRoutes();

$app->run();