脱Auto Layout NavigationView編

## はじめに

最近コードでレイアウトを組んでいるのでその備忘録。ネット上にあまり情報がなかったので残しときます。改善点などがあればコメントして欲しいです。🙇‍♂️
完成するアプリの動きとしては
![Simulator Screen Shot - iPod touch (7th generation) - 2020-12-17 at 23.46.04.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/549093/39b1a334-192d-e5ae-9d2e-7fb7737b5a06.png) ![Simulator Screen Shot - iPod touch (7th generation) - 2020-12-17 at 23.46.11.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/549093/b23173b3-bff7-610f-095b-9b4adcd6305a.png)
こんな感じ。
## 一つ目のViewController
​
`viewDidLoad()`の中で`barButton`を加えています。これを書いても追加されない時については後述しています。
​
`pushViewController`で遷移しています。モーダル遷移の時は`present()`を使います。
​

```swift
import UIKit
​
class FirstViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .blue
        navigationItem.title = "画面1"
        let barButton = UIBarButtonItem(barButtonSystemItem: .trash, target: self, action: #selector(addButtonTapped))
        navigationItem.rightBarButtonItem = barButton
    }
    
    @objc func addButtonTapped() {
        print("addButtonTapped")
        let secondVC = SecondViewController()
        self.navigationController?.pushViewController(secondVC, animated: true)
    }
}
```
## 二つ目のViewController
​
遷移先の画面ですが、特に何もしていません。
​
`view.background`で色を設定しないと遷移の時にカクカクになります。
​

```swift
import UIKit
​
class SecondViewController: UIViewController {
​
    override func viewDidLoad() {
        super.viewDidLoad()
        navigationItem.title = "画面2"
        view.backgroundColor = .green
    }
}
```
​
## SceneViewDelegate
​
UITabBarButtonが出ない！といったトラブルの原因は**UINavigationController**のrootViewControllerにUIBarButtonを加えたいViewControllerを設定することで解決すると思います。
​

```swift
import UIKit
​
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
​
    var window: UIWindow?
    var navigationController: UINavigationController?//加えた
​
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
      //ここから
        guard let _ = (scene as? UIWindowScene) else { return }
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            let firstVC = FirstViewController()
            navigationController = UINavigationController(rootViewController: firstVC)
            window.rootViewController = navigationController
            self.window = window
            window.makeKeyAndVisible()
        }
      //ここまで加えた
    }
//以下は同じ
    func sceneDidDisconnect(_ scene: UIScene) {
        // Called as the scene is being released by the system.
        // This occurs shortly after the scene enters the background, or when its session is discarded.
        // Release any resources associated with this scene that can be re-created the next time the scene connects.
        // The scene may re-connect later, as its session was not necessarily discarded (see `application:didDiscardSceneSessions` instead).
    }
​
    func sceneDidBecomeActive(_ scene: UIScene) {
        // Called when the scene has moved from an inactive state to an active state.
        // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
    }
​
    func sceneWillResignActive(_ scene: UIScene) {
        // Called when the scene will move from an active state to an inactive state.
        // This may occur due to temporary interruptions (ex. an incoming phone call).
    }
​
    func sceneWillEnterForeground(_ scene: UIScene) {
        // Called as the scene transitions from the background to the foreground.
        // Use this method to undo the changes made on entering the background.
    }
​
    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
    }
}
```