How to check if a user logged in?

My approach is with Filters:

PHP Code:

//app/Config/Filters.php
public $aliases = [
    'auth' => \App\Filters\Auth::class,
];
public $globals = [
    'before' => [
        'auth',
     ],
]; 


PHP Code:

//app/Filters/Auth.php
namespace App\Filters;
use CodeIgniter\Filters\FilterInterface;
use CodeIgniter\HTTP\RequestInterface;
use CodeIgniter\HTTP\ResponseInterface;
use Config\Services;

class Auth implements FilterInterface
{
    public function before(RequestInterface $request)
    {
    $session = Services::session();
        if ($session->has('auth'))
        { 
            if ($request->uri->getPath() == 'auth/login')
            {
                return redirect()->to('auth/profile');
            }
            if ($request->uri->getSegment(1) == 'admin')
            {
                 return redirect()->back();
            }
        } 
        else
        {
            if ($request->uri->getPath() != 'auth/login')
            {
                return redirect()->to('auth/login');
            }
        }
    }

    public function after(RequestInterface $request, ResponseInterface $response)
    {
    }

}