TweetFollow Us on Twitter

The Philosophy of Cocoa: Small is Beautiful and Lazy is Good

Volume Number: 18 (2002)
Issue Number: 8
Column Tag: Mac OS X

The Philosophy of Cocoa: Small is Beautiful and Lazy is Good

by Andrew C. Stone

I believe a programming renaissance is upon us--and Cocoa, Apple's high level object-oriented framework is at the heart of it. By wrapping complexity inside easy-to-use objects, Cocoa frees application developers from the burden of the minutiae that so often drives developers crazy. Instead, they can focus on what's special about their applications, and in a few lines of code, create a complete OS X application that seamlessly interoperates with all other OS X applications. And, for very little additional effort, they get AppleScriptability as well.

I've been living and breathing Cocoa and its various previous incarnations for 14 years now, and have noticed that my applications are getting more features with smaller amounts of code each year. This article will explore some of the truisms and gems hard earned by hanging in the trenches lo these many years.

Small is Beautiful

It's no coincidence that we use the term "architecture" for the overarching structure of an application. I received my baccalaureate in classical Architecture in the '70's when the visionaries of the time were rebelling against the huge concrete boxes that crushed the human scale and spirit. E. F. Schumacher, in Small is Beautiful -- A Study of Economics as if People Mattered:

    "What I wish to emphasise is the duality of the human requirement when it comes to the question of size: there is no single answer. For his different purposes man needs many different structures, both small ones and large ones, some exclusive and some comprehensive. Yet people find it most difficult to keep two seemingly opposite necessities of truth in their minds at the same time. They always tend to clamour for a final solution, as if in actual life there could ever be a final solution other than death. For constructive work, the principal task is always the restoration of some kind of balance. Today, we suffer from an almost universal idolatry of giantism. It is therefore necessary to insist on the virtues of smallness - where this applies. ..." (p. 54)

I believe this thinking still rings true 30 years later in cyber-architecture.

From the programming classic The Mythical Man Month by Frederick P. Brooks, Jr., we learned that the more programmers you throw at a project, the less likely the project will ever be finished! From this follows that a project should have one central architect, with rather fascist control over feature set and implementation, especially if you want it to ship in a timely fashion. Cocoa gives you the tools needed to build full-featured, world-class applications with just a handful of programmers. For best effect, these programmers should be lazy...

Lazy is Good

Laziness is a virtue, believe it or not! I often describe my style of a computer scientist as someone who is so lazy that they'll spend days writing software to save a minute each time the task is performed from then on. There are two forms of laziness that Cocoa embraces: lazy loading of objects and just plain lazy programming.

Bundle it Up

Lazy loading lets full-featured applications like Stone Design's Create(R), a three-in-one illustration, page layout and web authoring app, launch in just a few seconds. Compare that to a legacy Carbon application with half the features which takes minutes to launch! By using dynamically loaded bundles, you do not use memory or resources until the end user actually needs that particular feature and its related resources. Moreover, you can update and distribute just the tiny bundle instead of the whole application should, heaven forbid, a bug be found!

To use dynamically loaded bundles, you need to be able to compile your application without actually referencing the loadable object directly. We do this runtime magic by only referring to the dynamically loaded class, the principal class of the bundle, by its name as a string.

Typically, the types of objects that do well being loaded dynamically are the numerous special editors and interfaces in a program, such as an arrow or pattern editor and the classes it needs to provide the interface. The following conditions make up a good candidate for a loadable bundle:

  • Has resources that are not always used each session

  • Doesn't contain core data model classes (these should be linked)

A typical example might have an NSWindowController subclass and perhaps some custom views and images in the bundle. We load this type of bundle by having it respond to the class method "+sharedInstance", since you usually only need one of these objects per application:

- (void)loadAUniqueInterfaceObjectAction:(id)sender {
    // we only use the name of the bundle, not its class
    // which would cause an undefined symbol when linking:
    [[[NSApp delegate] sharedInstanceOfClassName:@"MyUniqueController"] showWindow:self];
}

But, with the introduction of sheets, two or more documents may want to load the same bundle (for example, a custom zoom sheet) at the same time. In this case, you'll want a unique instance, which will be released after use. These principal classes of bundles need only respond to -(id)init, which all objects do anyway since they inherit from NSObject which implements -(id)init;

- (void)loadAPerDocumentInterfaceObjectAction:(id)sender {
   [[[NSApp delegate] instanceOfClassName:@"MyPerDocumentController"] showWindow:self];
}

And, because we are lazy and more importantly, good programmers, we filter both of these methods through one factored method, -(id)instanceOfClassName:(NSString *)name shared:(BOOL)shared like this:

- (id)sharedInstanceOfClassName:(NSString *)name
{
    return [self instanceOfClassName:name shared:YES];
}
- (id)instanceOfClassName:(NSString *)name {
   return [self instanceOfClassName:name shared:NO];
}

And here's the non-linked bundle loading code for both of them, which we place for convenience in the globally available [NSApp delegate] class:

- (id)instanceOfClassName:(NSString *)name shared:(BOOL)shared
{
    id obj = nil;
    NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"bundle"];
    if (path) {
        // we found the bundle, now load it:
        NSBundle *b = [[NSBundle allocWithZone:NULL] initWithPath:path];
       // if it loads, see if it has a valid principalClass - this is set in PB's target inspector
        if ((b != nil) && ([b principalClass] !=NULL)) {
     // here is the only difference between a single shared instance
     // and a new one every time:
            if (shared) obj = [[b principalClass] sharedInstance];
            else obj = [[[b principalClass] allocWithZone:NULL] init];
        } else {
   // This is for debugging in case it can't be loaded:
   NSLog(@"Can't Load %@!\n", path);
        }
    } else NSLog(@"Couldn't find %@ bundle!\n",name);
    return obj;
}

Code Lazily

Lazy programming means "Use the 'Kit, Luke!" Every standard data structure and a complete set of API's are already available to you, so there is rarely a need to reinvent your own. Therefore, this lazy programming axiom has a corollary:

If it's hard to do or understand, it's wrong

By this I mean any coding solution that involves convoluted logic or going beneath the API (using undocumented methods) is probably not the right approach. Taking the time to understand what's already offered to you is well worth the effort, because Cocoa, and its underlying frameworks, Foundation and AppKit, have evolved over 16 years to provide the basic building blocks of an object oriented solution. Many times when I'm adding a new feature, I'll try one brute force approach, notice how cumbersome it is, re-read the AppKit or Foundation API and find a much a better solution involving much less code.

For example, I recently added a "Clone Client" feature to TimeEqualsMoney(TM) - take the current document's data, remove the individual time entries, create a new document with all the same settings except no time entries. It was six lines of code and it worked the first time:

- (void)cloneDocumentAction:(id)sender {
    // make a new untitled - have it read our document:
    NSMutableDictionary *doc = [self workDocumentDictionary];
    MyDocument *newDoc = [[NSDocumentController sharedDocumentController]
openUntitledDocumentOfType:DocumentType display:NO];
    [doc removeObjectForKey:WorkKey];
    [newDoc loadDataRepresentation:[[doc description] dataUsingEncoding:NSASCIIStringEncoding] 
    ofType:DocumentType];
    [newDoc makeWindowControllers];
    [[[newDoc windowControllers] objectAtIndex:0] showWindow:self];
}

Instead of hiring programmers, why not let the entire Cocoa team at Apple be your engineers? When you use the Kit and Apple puts in new functionality and bug fixes, your application automatically gains these features and fixes. Your efforts should be focused on creating a mapping between the real world problems you are solving and the objects that represent them. Which brings me to my next point:

Put The Code Where It Belongs

One of the biggest challenges facing newcomers to Object Oriented Programming is placing code in the right object. Because many of us grew up with "procedural" languages like Basic, Pascal, and C, and because old habits die hard, we need to let go of trying to tell things what do to do, and instead, let them figure it out for themselves. Let's say we have a document which is a list of pages, which contains a list of graphics, which are simple graphics or groups, which contain a list of graphics, which are graphics or groups which contain, etc... And let's say we want to set the "isVisible" state of all the graphics in the document.

The procedural approach would be to assume absolute knowledge over this hierarchy, and you'd blithely code something like this:

@implementation MyDocument
// please don't do this!
- (void)setAllObjectsVisible:(BOOL)isVisible {
    unsigned int i, pageCount = [_pages count];
    for (i = 0; i < pageCount; i++) {
        Page *p = [_pages objectAtIndex:i];
        NSArray *graphics = [p graphics];
        unsigned int j, graphicsCount = [graphics count];
        for (j = 0; j < graphicsCount; j++) {
            Graphic *g = [graphics objectAtIndex:j];
            if ([g isKindOfClass:[Group class]) {
                NSArray *groupGraphics = [g graphics];
                unsigned k,groupGraphicsCount = [groupGraphics count];
                for (k = 0; k < groupGraphicsCount; k++) {
   // since this only recurses one level, this code is wrong as
   // well as very hard to read and maintain!!!
   Graphic *groupedGraphic = [groupGraphics objectAtIndex:k];
   [k setVisible:isVisible];
                }
            else [g setVisible:isVisible];
        }
    }
)
// the OO way:
@implementation MyDocument
- (void)setAllObjectsVisible:(BOOL)isVisible {
     [_pages makeObjectsPerformSelector:@selector(setAllObjectsVisible:) withObject:(id)isVisible];
}
...
@implementation Page
- (void)setAllObjectsVisible:(BOOL)isVisible {
     [_graphics makeObjectsPerformSelector:@selector(setVisible:) withObject:(id)isVisible];
}
....
// groups need to recurse down the hierarchy until individual graphics
// are found...
@implementation Group
- (void)setVisible:(BOOL)isVisible {
    [_graphics makeObjectsPerformSelector:@selector(setVisible:) withObject:(id)isVisible];
}
@implementation Graphic
- (void)setVisible:(BOOL)isVisible {
   // only do work if you absolutely have to - remember LAZY!
    if (_isVisible != isVisible) {
   // you'd probably do undo manager stuff here
   _isVisible = isVisible;
   // alert page we need to be redrawn
   [self tellMyPageToInvalidateMyBounds];
    }
}
...

Conclusion

The more you understand object oriented programming and Cocoa, the smaller and more reusable your applications will become. And they will load with lightning speed! But more importantly, you'll have less code to maintain which means less bugs, less headaches and more time to enjoy life.


Andrew Stone, CEO of Stone Design, www.stone.com, has been the principal architect of several solar houses and over a dozen Cocoa applications shipping for Mac OS X.

 
AAPL
$102.13
Apple Inc.
+1.24
MSFT
$44.87
Microsoft Corpora
-0.14
GOOG
$571.00
Google Inc.
-6.86

MacTech Search:
Community Search:

Software Updates via MacUpdate

Viber 4.2.2 - Send messages and make cal...
Viber lets you send free messages and make free calls to other Viber users, on any device and network, in any country! Viber syncs your contacts, messages and call history with your mobile device,... Read more
Cocktail 7.6 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
LaunchBar 6.1 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
BBEdit 10.5.12 - Powerful text and HTML...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
Microsoft Office 2011 14.4.4 - Popular p...
Microsoft Office 2011 helps you create professional documents and presentations. And since Office for Mac 2011 is compatible with Office for Windows, you can work on documents with virtually anyone... Read more
TextWrangler 4.5.10 - Free general purpo...
TextWrangler is the powerful general purpose text editor, and Unix and server administrator's tool. Oh, and also, like the best things in life, it's free. TextWrangler is the "little brother" to... Read more
BitTorrent Sync 1.4.72 - Sync files secu...
BitTorrent Sync allows you to sync unlimited files between your own devices, or share a folder with friends and family to automatically sync anything. File transfers are encrypted. Your information... Read more
Cyberduck 4.5.2 - FTP and SFTP browser....
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
Tinderbox 6.0.3 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more

Latest Forum Discussions

See All

Mobile Convolution (Music)
Mobile Convolution 1.0.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0.0 (iTunes) Description: | Read more »
Invaders! From Outer Space Review
Invaders! From Outer Space Review By Rob Thomas on August 27th, 2014 Our Rating: :: RETRO NOSTALGIAUniversal App - Designed for iPhone and iPad It’s a shame that Invaders! doesn’t offer deeper gameplay, as this retro-inspired... | Read more »
Spooklands Review
Spooklands Review By Jennifer Allen on August 27th, 2014 Our Rating: :: ONE-TOUCH SHOOTERUniversal App - Designed for iPhone and iPad One-touch simultaneously controls your direction and your weapon in this unique arena shooter.   | Read more »
Heroes of Order & Chaos Add Twitch I...
Heroes of Order & Chaos Add Twitch Integration, New Heroes, and More Posted by Ellis Spice on August 27th, 2014 [ permalink ] | Read more »
Foodie Yama Review
Foodie Yama Review By Jennifer Allen on August 27th, 2014 Our Rating: :: BRIEFLY HOOKSUniversal App - Designed for iPhone and iPad Foodie Yama will draw you in for a brief while, and you’ll never be entirely sure why.   | Read more »
Spotify Connect Turns One, Now Supports...
Spotify Connect Turns One, Now Supports New Devices Posted by Ellis Spice on August 27th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
The Rise of PicsaStock and How You Can M...
We all take plenty of photos, right? That’s the joy of having a reasonably powerful camera in your pocket, thanks to your trusty iPhone and a bevy of similarly useful apps. Wouldn’t it be great to make some money out of those snaps? While your... | Read more »
Appointment With F.E.A.R Review
Appointment With F.E.A.R Review By Jennifer Allen on August 27th, 2014 Our Rating: :: CAMP DELIGHTUniversal App - Designed for iPhone and iPad Ever wanted to be a superhero? Appointment With F.E.A.R is a fine way to live that dream... | Read more »
Indie MOBA ÆRENA’s 2.0 Summer Update Bri...
Indie MOBA ÆRENA’s 2.0 Summer Update Brings New Missions, Skins, and a Champion Posted by Jessica Fisher on August 27th, 2014 [ permalink | Read more »
Ultra Drift Review
Ultra Drift Review By Rob Thomas on August 27th, 2014 Our Rating: :: ULTRA DULLUniversal App - Designed for iPhone and iPad Ultra Drift is fine in concept, but the execution runs head-first into the wall. And so will you. Over and... | Read more »

Price Scanner via MacPrices.net

The iPad’s Real Competitive Challenger (Not S...
It’s been my contention for some time that the iPad is suffering from something of an identity crisis, and I suspect that may be a factor in slackening sales this year. Apple can’t seem to decide... Read more
13-inch 2.6GHz/256GB Retina MacBook Pro on sa...
B&H Photo has the 13″ 2.6GHz/256GB Retina MacBook Pro on sale for $1379 including free shipping plus NY sales tax only. Their price is $120 off MSRP. Read more
Life Inventory iOS Apps – Learn to Know Thyse...
James Hollender’s Life Inventory apps s are now on sale with 20% off thru Labor Day, 09/01/2014. This is a great opportunity to get started on that Moral Inventory you’ve been putting off doing for... Read more
Pocket Watch, LLC. Reveals Cloud Server For P...
Beaumont, Texas based Pocket Watch, LLC. has announced the availability of its new ActivePrint Cloud Server Powered by Raspberry Pi. With this small standalone box almost any USB printer or available... Read more
902it Simplifies Area Code Changes For Nova S...
The east coast Canadian provinces of Nova Scotia and Prince Edward Island are phasing in 10 digit telephone dialing, to be fully in place by November, in order to accommodate a second area code to... Read more
Boomerang iPad Stand Mounts Your iPad Anywher...
Boomerang, a Mountable Stand with Multiple Viewing Angles, is now available for iPad Air. Boomerang combines several functions that aim to expand your iPad’s potential in one, elegant product. The... Read more
Retina MacBook Pros available starting at $10...
The Apple Store has Apple Certified Refurbished 13″ and 15″ MacBook Pros available starting at $929. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz MacBook Pros (4GB RAM/... Read more
Apple 27-inch Thunderbolt Display (refurbishe...
The Apple Store has Apple Certified Refurbished 27″ Thunderbolt Displays available for $799 including free shipping. That’s $200 off the cost of new models. Read more
Apple offers free $25 iTunes gift card with p...
The Apple Store is offering a free $25 iTunes Gift Card with the purchase of a $99 Apple TV for a limited time. Shipping is free. Read more
Apple’s 2014 Back to School promotion: $100 g...
 Apple’s 2014 Back to School promotion includes a free $100 App Store Gift Card with the purchase of any new Mac (Mac mini excluded), or a $50 Gift Card with the purchase of an iPad or iPhone,... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.