High-Level App Design/Architecture

Question

I've done a fair amount of iOS development in the past couple of years, so I'm pretty familiar with iOS architecture and app design (everything's a ViewController that you either push, pop, or stick into tab bars). I've recently started exploring proper Mac app development and feel a little lost. I'd like to really just have a sanity check and maybe some advice as to what the proper way to build an app like this is:

I'd like to build a library-style, single window app, that will spawn additional windows during its operation, but not as full-blown documents. The main window will be laid out much like OS X Lion's Mail.app, with a three-wide split view containing:

1. A source list, or high-level topic selection
2. A list view of items pertaining to the topic selected in the first pane
3. A detail view, which shows the details of the object selected in the middle pane

Like I said, really similar to Mail.app as far as looks go.

My question is really how to glue all this together from inside XCode. Here's where my confusion lies so far:

• The default project generated a NIB with a main menu and window. I like to encapsulate functionality, so should I make a window controller for this window and somehow hook it up in Interface Builder, or does window-specific functionality belong somewhere else?

• If possible, I'd like each of my three panes to be separate view controllers. I created three NSViewController subclasses (XCode automatically generated NIBs), and added (to the main menu/window NIB) view controller objects with each class specified, hooking up each one's view property to one of the three Custom View generic NSView objects I dropped into the NSSplitView. When I tried to set each view controller's NIB, only the main menu/window NIB appeared in the drop-down, and typing the desired one by hand seemed to have no effect (the view's contents didn't actually appear when running the app). This makes me think I'm doing something wrong.

• I'm a little fuzzy on what types of views I should use for each of the first two panes. I'll obviously build a custom one for the final pane, but it seems like the first two should be present in the Cocoa framework already.

Anyway, if I'm doing completely the wrong thing, don't bother addressing my questions; just tell me what I should be doing instead. I think I just need a proper Mac developer to point me in the right direction.

Answer 1

With regard to your first question, you don't need to use the main window that Apple supplies in MainMenu.xib. If you want, you are free to delete that window from the nib and then instantiate an NSWindowController in your applicationDidFinishLaunching: delegate method which then loads and controls the main window.

You are definitely confused about NSViewController, which is not really all that surprising, since you might assume that it works like UIViewController.

In fact, NSViewController is completely different to UIViewController and does not have the same level of Interface Builder support. You can't place a view controller in a window in IB, for example, whereas this is standard practice on iOS. NSViewController is a relatively new class on the Mac and generally you use it to load views programmatically and manage the view content.

The class that most closely maps to UIViewController on the Mac is NSWindowController. This has been around a lot longer than NSViewController and in fact many Mac apps don't use NSViewController at all.

Generally, each window in your app should have a window controller managing it. You can use subclasses of NSWindowController to handle a lot of the functionality for each window.

If you want to use NSViewController, then you should use your window controller to manage those view controller objects. This is generally done programmatically due to the aforesaid lack of Interface Builder support. Each NSViewController instance loads its view from a specific nib file. You generally don't add view controllers in Interface Builder.

For your source list you would generally use an NSOutlineView if you have multiple sections or an NSTableView. These two objects are used whenever you need a list of items. NSOutlineView is hierarchical, whereas NSTableView is flat.

I hope this helps.