Lost In Views - Best Way to Transition Between UIViewControllers

Question

I have an iPhone / iPad application that manages its numerous view controllers via a UINavigationController and UITabViewController. The UINavigationController handles the majority of the user interaction and the UITabViewController handles user settings/preferences.

My app delegate initializes the UINavigationController and pushes the first view controller. Settings (the UITabViewController) can be accessed via a button on the navigation controller's menu bar; the user can return to the main application (the UINavigationController) via a button on the UITabViewController.

My question is: what should I be doing with the UINavigationController (and its stack of view controllers) when I show the UITabViewController and vice-versa? Is there any reason to remove/release/recreate each parent controller as the user switches between the two, or should I be adding/removing each parent controller's view to my app's window?

It seems that the first option would be more mindful of memory/resources, however these benefits might get overshadowed by the processing cost to re-alloc/init the view controllers each time.

Thanks.

Answer 1

You do not have to manage the navigation controller's stack manually. What I would do is present your settings view controller as a modal view. You would do this at the navigation controller level.

Assume that settingsViewController is a property of your main view controller.

self.settingsViewController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal
[self.navigationController presentModalViewController:self.settingsViewController animated:YES];

Answer 2

I assume you mean UITabBarController.

If your navigation view would show up in the tab view for a tab item, I would suggest let the tab bar controller to be the root view controller of your application (and therefore always seen in the app).

If your navigation view is the main view, and the user simply opens up the tab bar view for settings etc. and will return for the navigation view, then modally presenting the tab bar controller is the right way.

In the first case (the navigation controller IN the tab bar controller), you would not care for adding/removing or allocating/releasing views as the UIKit will manage it for you.

In the second case you may create a tab bar controller when you want to show it. presentModalViewController will retain the view controller so you can release it immediately after you send the message. If you want to hold the view controller then you create one when the application is loaded and retain it in the navigation controller (and the navigation controller will always remain in the memory).