Xcode11-建立项目UISceneDelegate

UISceneDelegate

• 在Xcode11中新建项目，发现从iOS13开始，AppDelegate中再也不管理Window，而是将功能迁移到了SceneDelegate中。

• 首先看一下info.plist 的变化

• enable Multipe Windows --- 是否容许分屏
• Scene Configuratiton --- 屏幕配置项
• Application Session Role --- 程序屏幕配置规则（为每一个Scene指定规则）
• Configuration Name --- 配置名称
• Delegate Class Name --- 代理类名称
• Storyboard Name --- Storyboard名称

• 根据上面配置，咱们能够解读为，建立项目时，系统默认为咱们作了设置，一个名为Default Configuratiton 的默认配置，代理类名称为SceneDelegate,入口名为Main的Storyboard，
• AppDelegate中代码以下

#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];
}

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那么问题来了，想要自定义Window,不经过Storyboard建立，该如何操做?

在iOS13及以上系统

• 若是继续使用SceneDelegate，须要将info.plist中的Storyboard Name选项删除（即不指定Storyboard）
• SceneDelegate中代码修改以下：

- (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions {
    if (@available(ios 13, *)) {
         if (scene) {
             self.window = [[UIWindow alloc] initWithWindowScene:(UIWindowScene *)scene];
             self.window.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
             UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:[[ViewController alloc]init]];
             self.window.rootViewController = nav;
             [self.window makeKeyAndVisible];
         }
     }
}

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低于iOS13的系统

• 删除info.plist文件中的Application Scene Manifest选项
• 删除SceneDelegate文件
• 删除AppDelegate中的SceneDelegate方法
• AppDelegate.h中添加

@property (strong, nonatomic) UIWindow *window;
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• AppDelegate修改代码以下：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    ViewController * vc = [[ViewController alloc]init];
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:vc];
    self.window.rootViewController = nav;
    [self.window makeKeyAndVisible];
    return YES;
}
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