iOS ~ 移除SceneDelegate

1cfab85bffee390e5ca6179f54e7cd4049480.jpg

一、不使用SceneDelegate：

①在Objective-C项目中：移除SceneDelegate

1.先直接删除SceneDelegate.h/.m文件

2.在AppDelegate.h添加@property (strong, nonatomic) UIWindow * window;属性

#import 
@interface AppDelegate : UIResponder 
@property (strong, nonatomic) UIWindow * window;
@end

3.移除UIScene代理

移除之前

#import "AppDelegate.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    return YES;
}

#pragma mark - UISceneSession lifecycle
- (UISceneConfiguration *)application:(UIApplication *)application configurationForConnectingSceneSession:(UISceneSession *)connectingSceneSession options:(UISceneConnectionOptions *)options {
    // Called when a new scene session is being created.
    // Use this method to select a configuration to create the new scene with.
    return [[UISceneConfiguration alloc] initWithName:@"Default Configuration" sessionRole:connectingSceneSession.role];
}//移除
- (void)application:(UIApplication *)application didDiscardSceneSessions:(NSSet *)sceneSessions {
    // 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.
}//移除
@end

移除之后

#import "AppDelegate.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    return YES;
}
@end

4.最后在info.plist文件中移除Application Scene Manifest

②在Swift项目中：移除SceneDelegate

1.这是新建一个Swift项目是默认的项目文件结构:

截屏.png

2.直接删除SceneDelegate.swift这个文件 ；

3.在Info.plist中删除Application Scene Manifest相关：

选中的这个蓝色部分.png

4.在 AppDelegate.swift 中删除和UISceneSession相关的东西(红框中的函数)：

截屏.png

5.在AppDelegate.swift中新建UIWindow相关:

@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        
        let vc = ViewController()
        window?.backgroundColor = .white;
        window?.rootViewController = UINavigationController(rootViewController: vc)
        window?.makeKeyAndVisible()
        
        print("hello，world");
        
        return true
    }
}

因为现在默认启动程序时页面的背景默认时黑色的，可以在window这里设置背景为白色。

6.现在运行项目就可以正常运行了。

二、使用SceneDelegate，（多Scene，仅ipad有效）

xcode11创建项目新增SceneDelegate文件，AppDelegate文件结构也发生变化，在AppDelegate.h文件中没有了window属性，而是在SceneDelegate.h中，可见AppDelegate不管理window而是交给SceneDelegate。由于这些是ios13新增，所以SceneDelegate在ios13以下的系统是不支持。所以xcode11创建的项目如要做一下处理：

如果App不需要支持多个scene，同时兼容ios13以下，可以删除info.plist文件中的Application Scene Manifest的配置数据。在AppDelegate.h中添加window属性，同时删除UISceneSession的生命周期方法。和以前的使用方式一样。可参考iOS移除SceneDelegate
如果在ios13中支持多scene，原先AppDelegate的生命周期方法不再起作用。而是在SceneDelegate中使用UIScene提供的生命周期方法

开启支持多scene(仅iPad有效)

image

由于勾选分屏，在info.plist 中 Application Scene Manifest -> enable Multipe Windows 设置为YES.

image

默认在info.plist中进行了配置， 不用实现该方法也没有关系。如果没有配置就需要实现这个方法并返回一个UISceneConfiguration对象。

在上图中配置参数中Application Session Role 是个数组，每一项有三个参数，

Configuration Name: 当前配置的名字

Delegate Class Name: 与哪个Scene代理对象关联，

StoryBoard name: 这个Scene使用的哪个storyboard。

AppDelegate.m中多了UISceneSession的生命周期的代理方法

//1.如果没有在APP的Info.plist文件中包含scene的配置数据，或者要动态更改场景配置数据，需要实现此方法。 UIKit会在创建新scene前调用此方法。
//参数options是一个UISceneConnectionOptions类，官方解释：它包含了为什么要创建一个新的scene的信息。根据参数信息判断是否要创建一个新的scene
- (UISceneConfiguration *)application:(UIApplication *)application configurationForConnectingSceneSession:(UISceneSession *)connectingSceneSession options:(UISceneConnectionOptions *)options {
    NSLog(@"1");
    // Called when a new scene session is being created.
    // Use this method to select a configuration to create the new scene with.
    return [[UISceneConfiguration alloc] initWithName:@"Default Configuration" sessionRole:connectingSceneSession.role];
}
//方法会返回一个UISceneConfiguration对象，其包含其中包含场景详细信息，包括要创建的场景类型，用于管理场景的委托对象以及包含要显示的初始视图控制器的情节提要。 如果未实现此方法，则必须在应用程序的Info.plist文件中提供场景配置数据。
//总结下：默认在info.plist中进行了配置， 不用实现该方法也没有关系。如果没有配置就需要实现这个方法并返回一个UISceneConfiguration对象。
//在分屏中关闭其中一个或多个scene时候回调用。
- (void)application:(UIApplication *)application didDiscardSceneSessions:(NSSet *)sceneSessions {
    // 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.
    NSLog(@"2");
}

在SceneDelegate中不使用storyboard创建，手动创建新的window

- (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions {
   //在这里手动创建新的window
   if (scene) {
       UIWindowScene *windowScene = (UIWindowScene *)scene;
       self.window = [[UIWindow alloc] initWithWindowScene:windowScene];
       self.window.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
       self.window.rootViewController = [ViewController new];
       [self.window makeKeyAndVisible];
   }
}

SceneDelegate生命周期

- (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions {
    NSLog(@"场景加载完成");
}
- (void)sceneDidDisconnect:(UIScene *)scene {
    NSLog(@"场景已经断开连接");
}
- (void)sceneDidBecomeActive:(UIScene *)scene {
    NSLog(@"已经从后台进入前台");
}
- (void)sceneWillResignActive:(UIScene *)scene {
    NSLog(@"即将从前台进入后台");
}
- (void)sceneWillEnterForeground:(UIScene *)scene {
    NSLog(@"即将从后台进入前台");
}
- (void)sceneDidEnterBackground:(UIScene *)scene {
    NSLog(@"已经从前台进入后台");
}