Home/ Questions/Q 6973065
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-27T17:03:37+00:00

I am learning iOS programming through the Big Nerd Ranch guide by Hillegass and

  • 0

I am learning iOS programming through the Big Nerd Ranch guide by Hillegass and Conway. I’m writing an app of my own as I go through the book, and one of the questions that has been bugging me is exactly when I need to subclass UIViewController (and its ilk) and when I can just instantiate it.

For example, my app consists of generic building blocks: the interface is tabbed, and the tabs lead to a UITableView, a UINavigationController that creates UITableViews, and so on. Following the book’s instructions, I have subclassed UITableViewController to create the table views. However, in creating the UITabBarController that contains all of my app’s content, it seems sufficient to instantiate a UITabBarController and then add a bunch of views to it. (All of this is done in the application:didFinishLaunchingWithOptions: method of my app delegate. Since most of my app consists of simple combinations of basic UI parts, I’m trying to do build the UI programmatically whenever possible.)

I get the impression that what I should be doing is creating a subclass of UIViewController (or UITableViewController or whatever) for every interface in my project. This seems weird to me, since most of these classes would only ever be instantiated once. Am I just misunderstanding how OO should be used in this case? (I have a good amount of programming experience but relatively little has been with OOP.) Should I be creating a subclass for each and every screen that the user will see?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    So you have two types of UIViewControllers in iOS. “Container” viewControllers and “Content” viewcontrollers. Both are subclasses of UIViewController but have very different purposes.

    The Container type is what the UINavigationController and UITabController are. They are rarely subclassed and typically used as is (in fact, I believe Apple doesn’t allow the subclassing of UINavigationController at all). These “Containers” take care of moving “Content” view controller around for you. They do not have much content of their own, beyond adding things like a tab bar or a navigation bar.

    The “Content” view controller are the ones you create most of the time. You will rarely be able to use a UIViewController as is, because it will not have any functionality. That is why you subclass them. These are meant to represent a single “screenful” of content. So in effect, every “screen” the user sees should be controlled by a UIViewController subclass.

    The UITableViewController is simply a specialized sublass of UIViewController that already contains some methods for managing tables.

    The way the UIKit framework was designed was for you to use subclasses of UIViewController to display content and to use out-of-the-box “Container” controllers to facilitate the management of your UIViewController subclasses.

    • 0