有条件地从AppDelegate的情节提要中的不同位置开始

Question

我有一个故事板设置了正常的登录名和主视图控制器，主视图控制器是登录成功后用户导航到的视图控制器。我的目标是如果身份验证（存储在钥匙串中）成功，则立即显示主视图控制器，如果身份验证失败，则显示登录视图控制器。基本上，我想在AppDelegate中执行以下操作：// url request & response work fine, assume success is a BOOL here// that indicates whether login was successful or notif (success) {          // 'push' main view controller} else {          // 'push' login view controller}我知道方法performSegueWithIdentifier：但是该方法是UIViewController的实例方法，因此无法从AppDelegate中调用。如何使用现有的情节提要板来完成此任务？编辑：情节提要的初始视图控制器现在是导航控制器，没有连接任何东西。我使用了setRootViewController：区别，因为MainIdentifier是UITabBarController。这就是我的代码：- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{            BOOL isLoggedIn = ...;    // got from server response    NSString *segueId = isLoggedIn ? @"MainIdentifier" : @"LoginIdentifier";    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle:nil];    UIViewController *initViewController = [storyboard instantiateViewControllerWithIdentifier:segueId];    if (isLoggedIn) {        [self.window setRootViewController:initViewController];    } else {        [(UINavigationController *)self.window.rootViewController pushViewController:initViewController animated:NO];    }    return YES;}欢迎提出建议/改进！

Answer 1

我假设您的情节提要板被设置为“主情节提要板”（UIMainStoryboardFileInfo.plist中的键）。在这种情况下，UIKit将加载情节提要，并将其初始视图控制器设置为窗口的根视图控制器，然后再发送application:didFinishLaunchingWithOptions:到AppDelegate。

我还假设情节提要中的初始视图控制器是导航控制器，您要将主视图或登录视图控制器推入该导航控制器。

您可以向窗口询问其根视图控制器，并将performSegueWithIdentifier:sender:消息发送给它：

NSString *segueId = success ? @"pushMain" : @"pushLogin";

[self.window.rootViewController performSegueWithIdentifier:segueId sender:self];

Answer 2

我对这里提出的一些解决方案感到惊讶。

故事板中实际上不需要虚拟的导航控制器，无需在viewDidAppear：或任何其他黑客上隐藏视图并触发segues。

如果没有在plist文件中配置情节提要，则必须自己创建窗口和根视图控制器：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{        

    BOOL isLoggedIn = ...;    // from your server response

    NSString *storyboardId = isLoggedIn ? @"MainIdentifier" : @"LoginIdentifier";

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle:nil];

    UIViewController *initViewController = [storyboard instantiateViewControllerWithIdentifier:storyboardId];

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    self.window.rootViewController = initViewController;

    [self.window makeKeyAndVisible];

    return YES;

}

如果在应用程序的plist中配置了故事板，则在调用application：didFinishLaunching：时将已经设置了窗口和根视图控制器，并且将在窗口上为您调用makeKeyAndVisible。

在这种情况下，它甚至更简单：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{        

    BOOL isLoggedIn = ...;    // from your server response

    NSString *storyboardId = isLoggedIn ? @"MainIdentifier" : @"LoginIdentifier";

    self.window.rootViewController = [self.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:storyboardId];

    return YES;

}

Answer 3

如果您的情节提要的入口点不是UINavigationController：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    //Your View Controller Identifiers defined in Interface Builder

    NSString *firstViewControllerIdentifier  = @"LoginViewController";

    NSString *secondViewControllerIdentifier = @"MainMenuViewController";

    //check if the key exists and its value

    BOOL appHasLaunchedOnce = [[NSUserDefaults standardUserDefaults] boolForKey:@"appHasLaunchedOnce"];

    //if the key doesn't exist or its value is NO

    if (!appHasLaunchedOnce) {

        //set its value to YES

        [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"appHasLaunchedOnce"];

        [[NSUserDefaults standardUserDefaults] synchronize];

    }

    //check which view controller identifier should be used

    NSString *viewControllerIdentifier = appHasLaunchedOnce ? secondViewControllerIdentifier : firstViewControllerIdentifier;

    //IF THE STORYBOARD EXISTS IN YOUR INFO.PLIST FILE AND YOU USE A SINGLE STORYBOARD

    UIStoryboard *storyboard = self.window.rootViewController.storyboard;

    //IF THE STORYBOARD DOESN'T EXIST IN YOUR INFO.PLIST FILE OR IF YOU USE MULTIPLE STORYBOARDS

    //UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"YOUR_STORYBOARD_FILE_NAME" bundle:nil];

    //instantiate the view controller

    UIViewController *presentedViewController = [storyboard instantiateViewControllerWithIdentifier:viewControllerIdentifier];

    //IF YOU DON'T USE A NAVIGATION CONTROLLER:

    [self.window setRootViewController:presentedViewController];

    return YES;

}

如果您的情节提要的入口点是UINavigationController替换项：

//IF YOU DON'T USE A NAVIGATION CONTROLLER:

[self.window setRootViewController:presentedViewController];

与：

//IF YOU USE A NAVIGATION CONTROLLER AS THE ENTRY POINT IN YOUR STORYBOARD:

UINavigationController *navController = (UINavigationController *)self.window.rootViewController;

[navController pushViewController:presentedViewController animated:NO];