iOS -- When to create a child ViewController vs. a UIView Subclass?

Question

Maybe this is a silly question, but I've bumped into it a number of times during iOS Development.

Sometimes I'll develop a view component that I want to use on multiple screens, so I'll decide to subclass UIView and make it something I can use in multiple places.

Then, I start adding functionality to it. Maybe it needs to respond to an NSNotification, or it is supposed to respond to user touches.

At a certain point, I start wondering if I should really be making a UIViewController subclass, and add it to my UI as a child ViewController.

Is there any consensus on where to draw the line between adding some behaviors to a UIView, and when to create a full UIViewController?

Answer 1

You should use a controller anytime that you need to handle or control data. Views are supposed to be as stupid as possible, not knowing what they are displaying but rather where. You can easily subclass and reuse ViewControllers. A good example, say you need to retrieve a string (or text) from the user throughout your app via a popover controller and a modal. Create a generic subclass of UIViewController that has a view with a textfield and a button. You can then use this view and it's controller in any capacity you need. Reusing it in the popover, modal or anywhere else (and generally passing the data back through delegation). Since you are dealing with data you should not being using a sole subclass of UIView.

From my experience I subclass UIViewControllers more often then UIViews. It is a little difficult for me to understand if you are solely talking about Containers or reuse of views in general application workflow. Either way though it should be the same.