如何更改当前视图控制器？

Question

I have a login view controller which make a request to the server for authentification. Once it is success, I want the present view controller to be the home tab view controller of my application. I did try to use pushViewController:viewController or presentModalViewController or dismissModalViewControllerAnimated. Nothing works. You can take a look at the screenshot provided to understand my application flow.

Here is some sample code:

- (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

Figure out the solution. Instead of push the model view controller, I should change the rootViewController in the application delegate. It works well. Thanks for the help from everyone.