Simplifying a complicated Cocoa-Touch View Controller

Question

As I wire up my first fairly complicated Cocoa-Touch view I feel like I'm inadvertently slipping back into old procedural patterns and finding it difficult to shake them off...Though fully aware of many of the Cocoa (OO) design patterns I'm afraid I may be subverting them.

As such this view in question is quickly becoming unmanageable and I'm wondering if I might be approaching it the wrong way?!? The view is managed by a subclass of UIViewController. The view itself contains ±10 subviews. Some of these subviews "slide" in and out and contain their own subviews (controls, imageviews, etc) that slide along with them.

Without getting into too much detail I've found that I'm executing most (if not all, including animation) of my management code w/in the touchesBegan/Moved/Ended methods of my root View Controller. And it's become a mess of managing, setting & checking boolean properties. if (editingMode & panelAVisible).... if (editingMode & panelBVisible)... or *if (viewFlipped) { for (MyCustomView view in someArrayOfSubviews)} etc, etc... granted the UI of this app requires most of these views (or their contents) to be touched and moved by the user to different parts of the screen.

The main problems I'm trying to solve seems to be along the lines of: if viewA is present then you 3 views go hide (animated)...or, If viewB is touched then all objects contained in viewC are negative... etc.

Any clever (or rudimentary) OO approach to handling this? Perhaps make the subviews that contain views act as their own mini view controllers? I haven't been able to find too many (any?) examples of that though...

Answer 1

I think you should go along your last suggestion, make the subviews that contain views act as their own mini view controllers. Each (sub)view that presents a 'screen full of content' could/should be managed by its own view controller.

Animating between those views can be done with the build in navigation controller (you can actually hide the top bar of a navigation controller) such that you have the default slide animation. Otherwise you could indeed create your own animation while still using that navigation controller.

'The view itself contains ±10 subviews'. Some of these subviews "slide" in and out [..]'. These subviews you're talking about are perfect candidates for extraction from your one monolithic UIView.

The basic OO principle to use is how the navigation controller does it, by pushing and popping views on and off a stack. Each view pushed and popped is handled by its own view controller.

HTH

Edit: I now see you're not specifically talking about iPhone development. Still, have a look how its done there (especially the UINavigationController). You can still get the basic design idea

Answer 2

As you suggested at the end of your question, I would recommend having a subcontroller whenever you need logic for a particular subview. The point of a controller object is to keep track of state of the view and to encapsulate all that view logic that you were describing. Interface actions, such as if the user can move to a different screen, can invoke save logic, can create a new document, should be in the controller for that particular view. This will help maintain a separation of concerns between the various controllers and cut your convoluted logic down at the top level.

While it doesn't pertain to iPhone programming specifically, the book Cocoa Programming for Mac OS X contains good examples (especially in the chapter about how to do preference windows) of using subcontrollers and subviews in your application.