Removing ViewController after showing modally a second ViewController - ios

Question

Guys in my app I have some code in the app delegate method application:didFinishLaunchingWithOptions: that determines if the initial View Controller should be the LoginViewController or the MainViewController.
If the LoginViewController is showed first and the user logs in successfully I show the MainViewController modally with this piece of code:
UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
FSMainViewController *vc = (MainViewController *)[storyBoard instantiateViewControllerWithIdentifier:#"MainViewController"];
vc.loginViewController = self;
[self presentViewController:vc animated:YES completion:nil];
What I want to do next, after the MainController is showed on the screen, is remove the LoginViewController from memory so in the viewWillApper:animated: method of the MainViewController I use this code to remove (or at least try to) the LoginViewController:
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
if (self.loginViewController) {
[self.loginViewController dismissViewControllerAnimated:NO completion:nil];
}
}
Problem is that this code leads to strange behaviors like the MainViewController being removed from the screen and this error message showing up in the console.
Unbalanced calls to begin/end appearance transitions for <LoginViewController: 0xb06e350>
I also tried calling [self dismissViewControllerAnimated:NO completion:nil] in the completion block of the presentViewController:animated:completion method but still no luck, it didn't work.
What am I doing wrong? How can I remove from memory the underlying LoginViewController when the MainViewController is presented modally?

Answer 1

Don't present your main view controller if you want the login controller to go away, just make it the window's root view controller.
UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
FSMainViewController *vc = (MainViewController *)[storyBoard instantiateViewControllerWithIdentifier:#"MainViewController"];
Self.window.rootViewController = VC;

Answer 2

You can't dismissViewController after presenting another one on it or its presentingViewController. At here, you should dismiss LoginViewController first, then present MainViewController.
Otherwise, if you'd like pushViewController, you can call [self.navigationController setViewControllers: animated:] to remove LoginViewController.
If you think presentingViewController is just what you want, try something like this in application:didFinishLaunchingWithOptions:
if (self.loginViewController) { //Define loginViewController in appDelegate.h
[self dismissViewControllerAnimated:NO completion:^{
[self presentViewController:mainViewController animated:YES completion:nil];
}];
}
else{
[self presentViewController:mainViewController animated:YES completion:nil];
}