如何更改当前视图控制器？

Question

我有一个登录视图控制器，它向服务器发出请求以进行身份​​验证。一旦成功，我希望当前的视图控制器成为我的应用程序的主页选项卡视图控制器。我确实尝试使用pushViewController：viewController或presentModalViewController或dismissModalViewControllerAnimated。什么都行不通。您可以查看提供的屏幕截图，以了解我的应用程序流程。

以下是一些示例代码：

- (IBAction)facebookLoginButtonClick:(id)sender {

// get the app delegate so that we can access the session property
AppDelegate *appDelegate = [[UIApplication sharedApplication]delegate];

// this button's job is to flip-flop the session from open to closed
if (appDelegate.session.isOpen) {
    // if a user logs out explicitly, we delete any cached token information, and next
    // time they run the applicaiton they will be presented with log in UX again; most
    // users will simply close the app or switch away, without logging out; this will
    // cause the implicit cached-token login to occur on next launch of the application
    [appDelegate.session closeAndClearTokenInformation];

} else {
    if (appDelegate.session.state != FBSessionStateCreated) {
        // Create a new, logged out session.
        appDelegate.session = [[FBSession alloc] init];
    }

    // if the session isn't open, let's open it now and present the login UX to the user
    [appDelegate.session openWithCompletionHandler:^(FBSession *session,
                                                     FBSessionState status,
                                                     NSError *error) {
        // and here we make sure to update our UX according to the new session state
        [self dismissModalViewControllerAnimated:YES];
        UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle: nil];
        MainViewTabBarController *viewController = (MainViewTabBarController*)[mainStoryboard instantiateViewControllerWithIdentifier: @"mainPageTabBarId"];
        [[self navigationController] presentModalViewController:viewController animated:YES];
    }];
}

}

Answer 1

找出解决方案。我应该更改应用程序委托中的rootViewController，而不是推送模型视图控制器。它运作良好。感谢大家的帮助。