在 AppDelegate 中设置 InitialViewController

Posted 2023-02-23

【中文标题】在 AppDelegate 中设置 InitialViewController

【英文标题】：Setting InitialViewController in AppDelegate

【发布时间】：2014-05-13 15:13:00

【问题描述】：

我希望我的应用程序检查用户是否已登录。我有两个故事板，一个用于 3.5 英寸屏幕，一个用于 4.0 英寸屏幕。但是，我遇到的问题是，如果用户已登录，我不希望它显示 LoginViewController，它是我的 StoryBoards 中的 initialViewController 和 HomeViewController，它是您在登录后看到的视图。

下面是我的应用程序 didFinishLaunchingwithOptions

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

   // Override point for customization after application launch.
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
path = [path stringByAppendingPathComponent:@"u_id.plist"];
NSMutableDictionary *dico = [[NSMutableDictionary alloc] initWithContentsOfFile:path];

if ([dico objectForKey:@"u_id"]) 
    self.window = [[UIWindow alloc] init];

    CGSize iosDeviceScreenSize = [[UIScreen mainScreen] bounds].size;


    if (iosDeviceScreenSize.height == 480) 
        //Instantiate a new storyboard object using the storyboard file name
        UIStoryboard *iphone4 = [UIStoryboard storyboardWithName:@"iPhone4:4S:3Gs" bundle:nil];

        //homeView *view = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"MainViewController"];
        //UINavigationController *navcontrol = [[UINavigationController alloc] initWithRootViewController:view];

        //Instatiate the initial view controller object from the storyboard
        UIViewController *initialViewController = [iphone4 instantiateInitialViewController];

        //Instantiate a UIWIndow object and initialize it with the screen size
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

        //Set the initial view controller to be the root view controller of the
        self.window.rootViewController = initialViewController;
        //[self.window.rootViewController isKindOfClass:[homeView class]];

        //Set the window object to be the key window and show it
        [self.window makeKeyAndVisible];
    

    if (iosDeviceScreenSize.height == 568) 
        //iPhone5 and all other 4Inch screens
        //Instantiate a new storyboard object using the storyboard file named
        UIStoryboard *iphone5 = [UIStoryboard storyboardWithName:@"Main" bundle:nil];

        UIViewController *initialViewController = [iphone5 instantiateInitialViewController];
        //homeView *view = [[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"MainViewController"];
        //UINavigationController *navcontrol = [[UINavigationController alloc] initWithRootViewController:view];

        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        self.window.rootViewController = initialViewController;
        [self.window makeKeyAndVisible];
    
    [self.window makeKeyAndVisible];
 else 

    self.window = [[UIWindow alloc] init];

    CGSize iosDeviceScreenSize = [[UIScreen mainScreen] bounds].size;


    if (iosDeviceScreenSize.height == 480) 
        //Instantiate a new storyboard object using the storyboard file name
        UIStoryboard *iphone4 = [UIStoryboard storyboardWithName:@"iPhone4:4S:3Gs" bundle:nil];

        //Instatiate the initial view controller object from the storyboard
        UIViewController *initialViewController = [iphone4 instantiateInitialViewController];

        //Instantiate a UIWIndow object and initialize it with the screen size
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

        //Set the initial view controller to be the root view controller of the
        self.window.rootViewController = initialViewController;
        //[self.window.rootViewController isKindOfClass:[homeView class]];
        //Set the window object to be the key window and show it
        [self.window makeKeyAndVisible];
    

    if (iosDeviceScreenSize.height == 568) 
        //iPhone5 and all other 4Inch screens
        //Instantiate a new storyboard object using the storyboard file named
        UIStoryboard *iphone5 = [UIStoryboard storyboardWithName:@"Main" bundle:nil];

        UIViewController *initialViewController = [iphone5 instantiateInitialViewController];
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        self.window.rootViewController = initialViewController;
        [self.window makeKeyAndVisible];
    
    [self.window makeKeyAndVisible];




return YES;
 

如果用户已经登录，是否可以将我的 HomeView 设置为正在显示的视图，而不是 LoginView。

【问题讨论】：

您在 if-else 分支中拥有相同的代码。阅读rootViewController 的文档以了解您在做什么。

是的，它们是相同的代码，因为我不知道如何将我想要的特定视图作为 rootView。所以，我只是保留了代码，并在 Storyboard @A-Live 中手动设置了 initialViewController

如果您的目标是选择正确的视图，通常使用视图控制器。当然你可以将视图添加为窗口子视图，但不建议这样做。

【参考方案1】：

您可以选择首先实例化哪个视图控制器并使用不同的故事板方法 (instantiateViewControllerWithIdentifier:) 来获取它...

CGSize iosDeviceScreenSize = [[UIScreen mainScreen] bounds].size;
NSString *storyboardName = (iosDeviceScreenSize.height == 480)? @"iPhone4:4S:3Gs" : @"Main";
UIStoryboard *storyboard = [UIStoryboard storyboardWithName: storyboardName bundle:nil];

BOOL isUserLoggedIn = [dico[@"u_id"] boolValue];  // note the modern syntax for dictionary
NSString *vcId = (isUserLoggedIn)? @"LoggedInVCId" : @"NotLoggedInVCId";

// here's the punch line...
UIViewController *initialViewController = [storyboard instantiateViewControllerWithIdentifier:vcId];

另请注意，通过对storyboardName 和vcId 使用字符串变量，可以压缩代码并提高可读性。

【讨论】：

对不起，@"LoggedInVCId" : @"NotLoggedInVCId"，会被我自己定义的 VCIdentifire 替换吧？

这是我得到的错误无法为 UIMainStoryboardFile 'Main' 实例化默认视图控制器 - 也许未设置指定的入口点？ 和 BOOL isUserLoggedIn 正在返回指向整数转换初始化的指针不兼容的警告

哦，我已经解决了。我必须在情节提要中将视图设置为 Initial 来做到这一点，Hommie 你是最酷的.....但我也必须这样做以删除警告 NSString *value = dico[@"u_id"] ; BOOL isUserLoggedIn = [值 intValue]; // 注意字典的现代语法

明白了。很高兴它奏效了。很抱歉这个警告，那是我懒惰的编码。已编辑。