ログイン済みユーザーの表示画面の切り替え

import UIKit

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        let uid = AuthHelper().uid()
        if uid == "" {
            performSegue(withIdentifier: "login", sender: nil)
        } else {
            print(uid)
            //チャットリストを表示する処理
        }
    }
    
    @IBAction func onLogOut(_ sender: Any) {
        AuthHelper().signout()
        performSegue(withIdentifier: "login", sender: nil)
    }

}