ios - 如何在应用程序启动时以模态方式呈现 View Controller？

Question

我创建了一个仅在我的应用程序首次启动时出现的屏幕；它很好用。但是，我想在我的 Root View Controller 之上以模态方式呈现此屏幕(EditorsNoteViewController 是我想在首次启动时以模态方式呈现的屏幕)。有谁知道我会怎么做？这是我目前所拥有的:

Appdelegate.m

        - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
        {
            self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
            if ([[NSUserDefaults standardUserDefaults] boolForKey:@"HasLaunchedOnce"])
            {
                NSLog(@"not first launch");

                      self.viewController = [[UIStoryboard storyboardWithName:@"Main_iPhone" bundle:nil] instantiateViewControllerWithIdentifier:@"articlesNav"];
                self.window.rootViewController = self.viewController;

            }
            else
            {
                [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"HasLaunchedOnce"];
                [[NSUserDefaults standardUserDefaults] synchronize];



                self.viewController = [[UIStoryboard storyboardWithName:@"Main_iPhone" bundle:nil] instantiateViewControllerWithIdentifier:@"articlesNav"];
                self.window.rootViewController = self.viewController;


     EditorsNoteViewController *vc = [[EditorsNoteViewController alloc]init];
             [self.viewController.navigationController presentViewController:vc animated:YES completion:nil];

}
                [self.window makeKeyAndVisible];
    return YES;
}

Answer 1

我发现你必须打电话

[self.window makeKeyAndVisible];

在呈现 View Controller 之前