iOS 13 SceneDelegate适配(Xcode 11,适配ios13以下系统)

在Xcode11上新建一个iOS的带storyboard的项目

最低适配的系统改到iOS13以下后

解决方案一：删除SceneDelegate,还原到iOS13以前的版本(本人亲测可行)

1.给AppDelegate添加window属性
2.注释掉AppDelegate中UISceneSession Lifecycle下面的两个代理方法

3.删除Info.plist中的Application Scene Manifest字段

4.删掉SceneDelegate.swift文件

5.在AppDelegate中把之前的几个代理方法写回来

AppDelegate中的代码

//
//  AppDelegate.swift
//  MySceneDelegate
//
//  Created by macvivi on 2020/6/9.
//  Copyright © 2020 macvivi. All rights reserved.
//

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
     
    
    var window: UIWindow?
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
     
        // Override point for customization after application launch.
        return true
    }
    
    // MARK: UISceneSession Lifecycle
    
    //    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
     
    //        // Called when a new scene session is being created.
    //        // Use this method to select a configuration to create the new scene with.
    //        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    //    }
    //
    //    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set) {
     
    //        // Called when the user discards a scene session.
    //        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
    //        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
    //    }
    
    
    func applicationWillResignActive(_ application: UIApplication) {
     
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
    }
    
    func applicationDidEnterBackground(_ application: UIApplication) {
     
        
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    }
    
    func applicationWillEnterForeground(_ application: UIApplication) {
     
        // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    }
    
    func applicationDidBecomeActive(_ application: UIApplication) {
     
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    }
    
    func applicationWillTerminate(_ application: UIApplication) {
     
        
        
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }
    
    
    
}

方案二：iOS13以上系统使用SceneDelegate，iOS13以下系统不使用SceneDelegate（本人还未测试）

参考博客：
Xcode11新变化：SceneDelegate

其他参考博客：

iOS13 Scene Delegate详解

iOS 13 SceneDelegate适配