【Xcode】EntryPointを変更する方法

もくじ

0. 環境
1. Entry Pointとは
2. StoryBordから変更する
3. コードから変更する
4. [おまけ]初回起動時のみ特定の画面を表示させる

0. 環境

• MacBook Air M1
• Xcode 12.4

1. Entry Pointとは

• プログラムの開始される位置
• この記事では開始される画面の位置も含まれる

画面上で見ると以下の画像の矢印部分がEntry Pointを表している

アシスタントエディタで確認すると以下赤枠部分

2. StoryBordから変更する

ドラックアンドドロップで矢印を移動させる

Utilites areaから移動させる

Attributes inspector内のIs Initial View Controllerにチェクを入れる

3. コードから変更する

1. Main.storybordの遷移させたいViewControllerにStoryboad IDを設定する

• Identity Inspector 内のSotryboard IDを設定

• 今回はこのように設定
  • 1画面目 : FirstView
  • 2画面目 : SecondView

2. SceneDelegate.swift

1. 何も変更していないデフォルトの状態だとこのようなコードになっていると思います

   import UIKit
   
   class SceneDelegate: UIResponder, UIWindowSceneDelegate {
   
       var window: UIWindow?
   
   
       func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
           // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
           // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
           // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
           guard let _ = (scene as? UIWindowScene) else { return }
       }
   
       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.
       }
   
   
   }

2. sceneメソッド内に以下のコードのコードを追記します

   • この時、guard let _ =の_の部分をwindowに変更しています。

   func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
   	// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
   	// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
   	// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
   	guard let windowScene = (scene as? UIWindowScene) else { return }
   
   	window = UIWindow(windowScene: windowScene)
   	let storybard = UIStoryboard(name: "Main",bundle: nil)
    	
   	//  初めて起動しているか
   	if(lanchIsFIrstTme()){
   	    window?.rootViewController = storybard.instantiateViewController(identifier: "FirstView")
   	    firstLanch()
   	}else{
   	    window?.rootViewController = storybard.instantiateViewController(identifier: "SecondView")
   	}
   	
   	window?.makeKeyAndVisible()
   }

4. [おまけ]初回起動時のみ特定の画面を表示させる

一つ前で実装した切り替え処理とユーザーデフォルト機能を組み合わせて、初回起動かどうかを判定する

• 確認用メソッドと登録用メソッドを作成

  private let STORED_KEY = "lanched"
  
  func firstLanch(){
      return UserDefaults.standard.set(true,forKey: STORED_KEY)
  }
  
  func lanchIsFIrstTme() -> Bool{
      return !UserDefaults.standard.bool(forKey: STORED_KEY)
  }

• 一つ前で実装したコードを改変

  func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
      // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
      // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
      // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
      guard let windowScene = (scene as? UIWindowScene) else { return }
  
      window = UIWindow(windowScene: windowScene)
      let storybard = UIStoryboard(name: "Main",bundle: nil)
      
      //  初めて起動しているか
      if(lanchIsFIrstTme()){
          window?.rootViewController = storybard.instantiateViewController(identifier: "FirstView")
          firstLanch()
      }else{
          window?.rootViewController = storybard.instantiateViewController(identifier: "SecondView")
      }
      
      window?.makeKeyAndVisible()
  }

こんな感じになればOK

参考

https://stackoverflow.com/questions/10428629/programmatically-set-the-initial-view-controller-using-storyboards/47691073