The Chapter 4 example of a Windows based application, pages 85-91, drags and drops a View Controller onto the window and then populates the view with various objects.

But it seems that one can display objects on a window without creating a View Controller, and there appear to be examples on the web of doing just that.

I've created a Windows based application, dragged and dropped a UIWebView onto it, along with two toolbar buttons, and with appropriate connections had no difficulty using them, no View Controller declared or used.

Can anyone explain exactly when a View Controller becomes necessary?

One of the things I need to do in my app is start with a full page of HTML, displayed using a UIWebView, then when certain hyperlinks are clicked, pop-up JPEG images and other effects. For the JPEG pop-ups, could that be done by the "Adding a View Controller and Views Programmatically" on pages 91-95?

Thanks.

The UIViewController class has many delegate and template methods that are used regularly. If you place your interface directly on a window none of these methods are called. For example handling rotation. Your interface on the window, but not in a view - what happens if you change orientation?

Bob

I know paraphrasing is dangerous, but essentially a UIWindow is a crippled UIViewController? Can do basic things but not more complex things?

There was an error in my previous reply concerning UIWindow and UIResponder.
A UIWindow is basically the "real estate" for the various views to present themselves. You don't usually subclass a window. The customized behavior is contained in the ViewControllers. Since most programs have more than one view, and iOS typically has only one window, this makes sense. Each object, with its component parts, is self contained in its own class. There is additional functionality in a UIViewController than in a UIWindow because that is where the interface customization is supposed to be done.
I think of the UIWindow as a wall. On that wall I can place cabinets, paintings, pictures, a flat screen tv, projector screen, lights, speakers etc. and the wall is still just a wall. I can change, add and remove these objects as I wish. If I decide to make the wall a mural instead, I am stuck with that intruding on everything else. The window should be generic. If you customize the UIWindow with your interface objects directly you lose both the flexibility and the benefits of encapsulation, plus the additional functionality that is in the UIViewController.

A UIWindow is no more a crippled UIViewController, than a UIViewController is a crippled UITableViewController, or an NSObject is a crippled everything else.

Bob