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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

BetterTouchTool 2.332 - Customize multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Capture One 11.0.1.40 - RAW workflow sof...
Capture One is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 400 high-end cameras -- straight out of the box. It offers... Read more
Capture One 11.0.1.40 - RAW workflow sof...
Capture One is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 400 high-end cameras -- straight out of the box. It offers... Read more
GraphicConverter 10.5.4 - $39.95
GraphicConverter is an all-purpose image-editing program that can import 200 different graphic-based formats, edit the image, and export it to any of 80 available file formats. The high-end editing... Read more
Dash 4.1.3 - Instant search and offline...
Dash is an API documentation browser and code snippet manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
Microsoft OneNote 16.9 - Free digital no...
OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more
DEVONthink Pro 2.9.17 - Knowledge base,...
Save 10% with our exclusive coupon code: MACUPDATE10 DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research... Read more
OmniGraffle 7.6 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
iFinance 4.3.7 - Comprehensively manage...
iFinance allows you to keep track of your income and spending -- from your lunchbreak coffee to your new car -- in the most convenient and fastest way. Clearly arranged transaction lists of all your... Read more
Opera 50.0.2762.58 - High-performance We...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more

Latest Forum Discussions

See All

Around the Empire: What have you missed...
Around this time every week we're going to have a look at the comings and goings on the other sites in Steel Media's pocket-gaming empire. We'll round up the very best content you might have missed, so you're always going to be up to date with the... | Read more »
Everything about Hero Academy 2: Part 4...
In this part of our Hero Academy 2 guide, we're going to have a look at some of the tactics you're going to need to learn if you want to rise up the ranks. We're going to start off slow, then get more advanced in the next section. [Read more] | Read more »
All the best games on sale for iPhone an...
Another week has flown by. Sometimes it feels like the only truly unstoppable thing is time. Time will make dust of us all. But before it does, we should probably play as many awesome mobile videogames as we can. Am I right, or am I right? [Read... | Read more »
The 7 best games that came out for iPhon...
Well, it's that time of the week. You know what I mean. You know exactly what I mean. It's the time of the week when we take a look at the best games that have landed on the App Store over the past seven days. And there are some real doozies here... | Read more »
Popular MMO Strategy game Lords Mobile i...
Delve into the crowded halls of the Play Store and you’ll find mobile fantasy strategy MMOs-a-plenty. One that’s kicking off the new year in style however is IGG’s Lords Mobile, which has beaten out the fierce competition to receive Google Play’s... | Read more »
Blocky Racing is a funky and fresh new k...
Blocky Racing has zoomed onto the App Store and Google Play this week, bringing with it plenty of classic kart racing shenanigans that will take you straight back to your childhood. If you’ve found yourself hooked on games like Mario Kart or Crash... | Read more »
Cytus II (Games)
Cytus II 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: "Cytus II" is a music rhythm game created by Rayark Games. It's our fourth rhythm game title, following the footsteps of three... | Read more »
JYDGE (Games)
JYDGE 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Build your JYDGE. Enter Edenbyrg. Get out alive. JYDGE is a lawful but awful roguehate top-down shooter where you get to build your... | Read more »
Tako Bubble guide - Tips and Tricks to S...
Tako Bubble is a pretty simple and fun puzzler, but the game can get downright devious with its puzzle design. If you insist on not paying for the game and want to manage your lives appropriately, check out these tips so you can avoid getting... | Read more »
Everything about Hero Academy 2 - The co...
It's fair to say we've spent a good deal of time on Hero Academy 2. So much so, that we think we're probably in a really good place to give you some advice about how to get the most out of the game. And in this guide, that's exactly what you're... | Read more »

Price Scanner via MacPrices.net

Deals on clearance 15″ Apple MacBook Pros wit...
B&H Photo has clearance 2016 15″ MacBook Pros available for up to $800 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: – 15″ 2.7GHz Touch Bar MacBook Pro... Read more
Apple restocked Certified Refurbished 13″ Mac...
Apple has restocked a full line of Certified Refurbished 2017 13″ MacBook Airs starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: – 13″ 1.8GHz/8GB/128GB... Read more
How to find the lowest prices on 2017 Apple M...
Apple has Certified Refurbished 13″ and 15″ 2017 MacBook Pros available for $200 to $420 off the cost of new models. Apple’s refurbished prices are the lowest available for each model from any... Read more
The lowest prices anywhere on Apple 12″ MacBo...
Apple has Certified Refurbished 2017 12″ Retina MacBooks available for $200-$240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free.... Read more
Apple now offering a full line of Certified R...
Apple is now offering Certified Refurbished 2017 10″ and 12″ iPad Pros for $100-$190 off MSRP, depending on the model. An Apple one-year warranty is included with each model, and shipping is free: –... Read more
27″ iMacs on sale for $100-$130 off MSRP, pay...
B&H Photo has 27″ iMacs on sale for $100-$130 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27″ 3.8GHz iMac (MNED2LL/A): $2199 $100 off MSRP – 27″ 3.... Read more
2.8GHz Mac mini on sale for $899, $100 off MS...
B&H Photo has the 2.8GHz Mac mini (model number MGEQ2LL/A) on sale for $899 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Apple offers Certified Refurbished iPad minis...
Apple has Certified Refurbished 128GB iPad minis available today for $339 including free shipping. Apple’s standard one-year warranty is included. Their price is $60 off MSRP. Read more
Amazon offers 13″ 256GB MacBook Air for $1049...
Amazon has the 13″ 1.8GHz/256B #Apple #MacBook Air on sale today for $150 off MSRP including free shipping: – 13″ 1.8GHz/256GB MacBook Air (MQD42LL/A): $1049.99, $150 off MSRP Read more
9.7-inch 2017 WiFi iPads on sale starting at...
B&H Photo has 9.7″ 2017 WiFi #Apple #iPads on sale for $30 off MSRP for a limited time. Shipping is free, and pay sales tax in NY & NJ only: – 32GB iPad WiFi: $299, $30 off – 128GB iPad WiFi... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Data Center Site Selection and Strat...
# Apple Data Center Site Selection and Strategy Research Analyst Job Number: 83708609 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: Read more
Security Engineering Coordinator, *Apple* R...
# Security Engineering Coordinator, Apple Retail Job Number: 113237456 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: 40.00 **Job Read more
Firmware Engineer - *Apple* Accessories - A...
# Firmware Engineer - Apple Accessories Job Number: 113422485 Santa Clara Valley, California, United States Posted: 18-Jan-2018 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.