UIViewController did not deallocate itself

Question

I'm working on an app that changes it's rootViewController depending on it's state. To make a switch I use this code:

- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [self createManagedDocumentAndContext];

    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    NSString *storyboardId = [userDefaults boolForKey:@"Profile Created"] ? @"User Stats" : @"Profile";

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

    return YES;
}

To switch back I call this method from presented ProfileVC:

- (void)returnOldRootViewController
{
    UIWindow *currentWindow = [UIApplication sharedApplication].keyWindow;

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    OLDUserStatsVC *userStatsVC = [storyboard instantiateViewControllerWithIdentifier:@"User Stats"];
    userStatsVC.userProfile = self.userProfile;

    [currentWindow setRootViewController:userStatsVC];

    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setBool:YES forKey:@"Profile Created"];

}

THE PROBLEM: rootViewController is changed, but previous one is not deallocated. It stays on the "background" of the app - I can see it when VC changes to another one.

The question is how to release it properly? Thank you very much!

Answer 1

The real problem here is that you are changing the root view controller of the window. Don't do that. You should be setting this once and never again. There should be just one root view controller for the lifetime of the app.

Find another architecture for displaying the correct view controller and switching between them as desired. For example, they might both be children of the root view controller, or one might be a presented view controller in front of the other.