Publishing Date:2020-11-04

scene delegate에 대해 설명하시오

배경지식

AppDelegate에 이어서, xcode 프로젝트를 생성하면 SceneDelegate.swift 파일이 자동으로 생성된다.

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.
    }
}

UIWindowSceneDelegate

Use UIWindowSceneDelegate object to manage the life cycle of one instance of your app’s user interface

scene에서 발생하는 앱별 작업을 관리하는 추가적인 프로토콜로 scene의 life cycle을 관리한다. UISceneDelegate 속성을 따르며 scene의 상태에 따라 notification을 받거나 scene의 환경 변화(사이즈 변화 등)에 응답할 수 있다.

UISceneDelegate

Use UISceneDelegate object to manage life-cycle events in one instance of your app’s user interface

scene에서 발생하는 life cycle 이벤트를 관리

Scene

AppDelegate를 공부하면서 scene이

Methods

메소드는 scene에 영향을 끼치는 상태 변화(scene이 foreground, active, background)에 응답하도록 정의됨.

• scene(_:willConnectTo:options:)
  scene이 app에 추가함
• sceneDidDisconnect(_:)
  UIKit이 scene을 app에서 제거함
• sceneDidBecomeActive(_:)
  scene이 active되어 사용자 이벤트를 받을 수 있음
• sceneWillResignActive(_:)
  scene이 곧 active 상태에서 벗어나 사용자 이벤트를 받을 수 없음
• sceneWillEnterForeground(_:)
  scene이 곧 foreground에 올라가 사용자에게 보여짐
• sceneDidEnterBackground(_:)
  scene이 background로 들어감

Reference

Apple Docs- Scenes
Apple Docs- UIWindowSceneDelegate
Apple Docs- UISceneDelegate