rootViewControllerを足してloginとlogoutの遷移処理を書いた

chat-iOS/App/AppDelegate.swift

@@ -18,7 +18,7 @@ final class AppDelegate: UIResponder, UIApplicationDelegate {
         if #available(iOS 13, *) {
         } else {
             window = UIWindow(frame: UIScreen.main.bounds)
-            window?.rootViewController = Routes.decideRootViewController()
+            window?.rootViewController = RootViewController()
             window?.makeKeyAndVisible()
         }
         return true

chat-iOS/App/RootViewController.swift

@@ -0,0 +1,72 @@
+//
+//  RootViewController.swift
+//  chat-iOS
+//
+//  Created by 戸高新也 on 2020/07/13.
+//
+
+import UIKit
+import FirebaseAuth
+
+class RootViewController: UIViewController {
+
+    static var instance: RootViewController {
+        return UIApplication.shared.keyWindow!.rootViewController as! RootViewController
+    }
+
+    enum ViewType {
+        case login
+        case main
+    }
+
+    private var viewType: ViewType? {
+        didSet {
+            guard let type = viewType, oldValue != type  else { return }
+            switch type {
+            case .login:
+                currentViewController = UINavigationController(rootViewController: AuthTopViewBuilder.create())
+            case .main:
+                currentViewController = MainTabBarViewBuilder.create()
+            }
+        }
+    }
+
+    private(set) var currentViewController: UIViewController? {
+        didSet {
+            guard let currentViewController = currentViewController else { return }
+
+            addChild(currentViewController)
+            view.addSubview(currentViewController.view)
+            currentViewController.didMove(toParent: self)
+            currentViewController.view.frame = view.bounds
+
+            guard let oldViewController = oldValue else { return }
+
+            view.sendSubviewToBack(currentViewController.view)
+            UIView.transition(from: oldViewController.view, to: currentViewController.view, duration: 0.35, options: .transitionCrossDissolve) { _ in
+                oldViewController.willMove(toParent: nil)
+                oldViewController.view.removeFromSuperview()
+                oldViewController.removeFromParent()
+            }
+        }
+    }
+
+    override func loadView() {
+        super.loadView()
+        view.backgroundColor = .white
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        if Auth.auth().currentUser?.uid == nil {
+            self.viewType = .login
+        } else {
+            self.viewType = .main
+        }
+    }
+
+    func transition(to type: ViewType) {
+        self.viewType = type
+    }
+}

chat-iOS/App/SceneDelegate.swift

@@ -16,7 +16,7 @@ final class SceneDelegate: UIResponder, UIWindowSceneDelegate {
     func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
         guard let scene = (scene as? UIWindowScene) else { return }
         window = UIWindow(windowScene: scene)
-        window?.rootViewController = Routes.decideRootViewController()
+        window?.rootViewController = RootViewController()
         window?.makeKeyAndVisible()
     }
 }

chat-iOS/Views/Login/LoginViewController.swift

@@ -52,7 +52,7 @@ extension LoginViewController: LoginViewPresenterOutput {
 
     func transitionToMainTabBar(withUser user: User) {
         //TODO:- userを使ってMainTabBarへの遷移処理を書く
-        print(user.displayName)
+        RootViewController.instance.transition(to: .main)
     }
 
     func showAlert(withMessage message: String) {