TweetFollow Us on Twitter

Style For Cocoa Programmers

Volume Number: 21 (2005)
Issue Number: 7
Column Tag: Programming

Tips From Big Nerd Ranch

Style For Cocoa Programmers

by Aaron Hillegass, Chris Campbell, Marquis Logan

As developers and teachers, we spend a lot of time dealing with issues of style. Not just because we like to look cool for the ladies; code that is written by a stylish programmer is easier to read and maintain. The Cocoa community has developed idioms, and if you want other developers to be able to easily comprehend your code, you should follow those idioms.

Issue #1: Whitespace

Here is a perfect setter method that explicitly invokes key-value observing:

- (void)setBorderColor:(Color *)c
{
    if (c == borderColor) {
        return;
    }
    [self willChangeValueForKey:@"borderColor"];
    [c retain];
    [borderColor release];
    borderColor = c;
    [self didChangeValueForKey:@"borderColor"];
}

Notice the use of whitespace. In particular, we do not put spaces after colons. We do not put spaces after the type of the parameter (That is, "(Dog *)").

Also, notice that there are no comments. What this method does is self-evident from its name. Too many comments can be just as annoying as too few.

Issue #2: Grouping Methods

In an implementation file, methods should be grouped in a meaningful manner. In particular, we try to follow this order:

   Class methods
   Initializers and dealloc
   copyWithZone:
   isEqual:
   hash
   initWithCoder: and encodeWithCoder:
   action methods
   other methods (subgroup meaningfully)
   delegate methods
   accessor methods (in setter/getter pairs)

Use #pragma mark to show where a group of methods begins. The information will show up in the popup in Xcode. For example, you might insert these lines:

#pragma mark Coding methods
#pragma mark Color metrics
#pragma mark Accessors

So that your Xcode popup would look like this:


Figure 1.

Issue #3: Naming methods

If you have a method that returns the brightness of a border, it should be named thusly:

- (float)borderBrightness;

We do not put articles on method names:

- (float)theBorderBrightness;

We do not prefix methods with get-:

- (float)getBorderBrightness;

The exception to this rule is if the method is pass-by-reference:

float r, g, b;
[borderColor getRed	:&r 
              blue	:&b 
             green	:&g 
             alpha	:NULL];

If a method takes one argument and is prefixed with set-, it should be an accessor. In particular, an action method should never be prefixed with set-.

Issue #4: What Goes In The .h File

The primary purpose of your .h file is so that I can create an instance of your class and send messages to it. Many people put too much information in their .h files. Don't declare any of the following in the .h file:

1) Delegate methods.

2) Private methods.

3) Any methods in a protocol that you conform to. For example, if you have:

@interface Chowder : NSObject <NSCopying>

There is no reason to declare copyWithZone: in your .h file.

4) Any inherited or overridden methods.

Issue #5: Declaring Local Variables

Declare temporary variable in a "just-in-time" manner. When I'm reading your code, I don't want to have to scroll to the beginning of the method to figure out the type of a local variable. Move the declaration as close to the first use as possible.

The Analysis and Design Workshop

In a short column, it is easy to discuss small issues like code formatting and variable naming. For larger and deeper issues, we need a much bigger forum. At the ranch in August, we are hosting an "Analysis and Design Workshop." John Graziano, who had a major part in the design of Xcode, WebObjects Builder, and many of the animation systems at Pixar, will lecture and guide hands-on exercises that teach good design practices. He is going to focus on creating designs that make change and maintenance easy. John started developing these ideas at NeXT, and they have received much acclaim within NeXT, Apple, and Pixar. Bring your specifications, and go home with the beginnings of a really good design for your app. The workshop is August 15 - 19 in Atlanta. We hope to see you there.


Aaron Hillegass, Chris Campbell, Marquis Logan

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Whitethorn Games combines two completely...
If you have ever gone fishing then you know that it is a lesson in patience, sitting around waiting for a bite that may never come. Well, that's because you have been doing it wrong, since as Whitehorn Games now demonstrates in new release Skate... | Read more »
Call of Duty Warzone is a Waiting Simula...
It's always fun when a splashy multiplayer game comes to mobile because they are few and far between, so I was excited to see the notification about Call of Duty: Warzone Mobile (finally) launching last week and wanted to try it out. As someone who... | Read more »
Albion Online introduces some massive ne...
Sandbox Interactive has announced an upcoming update to its flagship MMORPG Albion Online, containing massive updates to its existing guild Vs guild systems. Someone clearly rewatched the Helms Deep battle in Lord of the Rings and spent the next... | Read more »
Chucklefish announces launch date of the...
Chucklefish, the indie London-based team we probably all know from developing Terraria or their stint publishing Stardew Valley, has revealed the mobile release date for roguelike deck-builder Wildfrost. Developed by Gaziter and Deadpan Games, the... | Read more »
Netmarble opens pre-registration for act...
It has been close to three years since Netmarble announced they would be adapting the smash series Solo Leveling into a video game, and at last, they have announced the opening of pre-orders for Solo Leveling: Arise. [Read more] | Read more »
PUBG Mobile celebrates sixth anniversary...
For the past six years, PUBG Mobile has been one of the most popular shooters you can play in the palm of your hand, and Krafton is celebrating this milestone and many years of ups by teaming up with hit music man JVKE to create a special song for... | Read more »
ASTRA: Knights of Veda refuse to pump th...
In perhaps the most recent example of being incredibly eager, ASTRA: Knights of Veda has dropped its second collaboration with South Korean boyband Seventeen, named so as it consists of exactly thirteen members and a video collaboration with Lee... | Read more »
Collect all your cats and caterpillars a...
If you are growing tired of trying to build a town with your phone by using it as a tiny, ineffectual shover then fear no longer, as Independent Arts Software has announced the upcoming release of Construction Simulator 4, from the critically... | Read more »
Backbone complete its lineup of 2nd Gene...
With all the ports of big AAA games that have been coming to mobile, it is becoming more convenient than ever to own a good controller, and to help with this Backbone has announced the completion of their 2nd generation product lineup with their... | Read more »
Zenless Zone Zero opens entries for its...
miHoYo, aka HoYoverse, has become such a big name in mobile gaming that it's hard to believe that arguably their flagship title, Genshin Impact, is only three and a half years old. Now, they continue the road to the next title in their world, with... | Read more »

Price Scanner via MacPrices.net

B&H has Apple’s 13-inch M2 MacBook Airs o...
B&H Photo has 13″ MacBook Airs with M2 CPUs and 256GB of storage in stock and on sale for up to $150 off Apple’s new MSRP, starting at only $849. Free 1-2 day delivery is available to most US... Read more
M2 Mac minis on sale for $100-$200 off MSRP,...
B&H Photo has Apple’s M2-powered Mac minis back in stock and on sale today for $100-$200 off MSRP. Free 1-2 day shipping is available for most US addresses: – Mac mini M2/256GB SSD: $499, save $... Read more
Mac Studios with M2 Max and M2 Ultra CPUs on...
B&H Photo has standard-configuration Mac Studios with Apple’s M2 Max & Ultra CPUs in stock today and on Easter sale for $200 off MSRP. Their prices are the lowest available for these models... Read more
Deal Alert! B&H Photo has Apple’s 14-inch...
B&H Photo has new Gray and Black 14″ M3, M3 Pro, and M3 Max MacBook Pros on sale for $200-$300 off MSRP, starting at only $1399. B&H offers free 1-2 day delivery to most US addresses: – 14″ 8... Read more
Department Of Justice Sets Sights On Apple In...
NEWS – The ball has finally dropped on the big Apple. The ball (metaphorically speaking) — an antitrust lawsuit filed in the U.S. on March 21 by the Department of Justice (DOJ) — came down following... Read more
New 13-inch M3 MacBook Air on sale for $999,...
Amazon has Apple’s new 13″ M3 MacBook Air on sale for $100 off MSRP for the first time, now just $999 shipped. Shipping is free: – 13″ MacBook Air (8GB RAM/256GB SSD/Space Gray): $999 $100 off MSRP... Read more
Amazon has Apple’s 9th-generation WiFi iPads...
Amazon has Apple’s 9th generation 10.2″ WiFi iPads on sale for $80-$100 off MSRP, starting only $249. Their prices are the lowest available for new iPads anywhere: – 10″ 64GB WiFi iPad (Space Gray or... Read more
Discounted 14-inch M3 MacBook Pros with 16GB...
Apple retailer Expercom has 14″ MacBook Pros with M3 CPUs and 16GB of standard memory discounted by up to $120 off Apple’s MSRP: – 14″ M3 MacBook Pro (16GB RAM/256GB SSD): $1691.06 $108 off MSRP – 14... Read more
Clearance 15-inch M2 MacBook Airs on sale for...
B&H Photo has Apple’s 15″ MacBook Airs with M2 CPUs (8GB RAM/256GB SSD) in stock today and on clearance sale for $999 in all four colors. Free 1-2 delivery is available to most US addresses.... Read more
Clearance 13-inch M1 MacBook Airs drop to onl...
B&H has Apple’s base 13″ M1 MacBook Air (Space Gray, Silver, & Gold) in stock and on clearance sale today for $300 off MSRP, only $699. Free 1-2 day shipping is available to most addresses in... Read more

Jobs Board

Medical Assistant - Surgical Oncology- *Apple...
Medical Assistant - Surgical Oncology- Apple Hill Location: WellSpan Medical Group, York, PA Schedule: Full Time Sign-On Bonus Eligible Remote/Hybrid Regular Apply Read more
Omnichannel Associate - *Apple* Blossom Mal...
Omnichannel Associate - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Read more
Cashier - *Apple* Blossom Mall - JCPenney (...
Cashier - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Blossom Mall Read more
Operations Associate - *Apple* Blossom Mall...
Operations Associate - Apple Blossom Mall Location:Winchester, VA, United States (https://jobs.jcp.com/jobs/location/191170/winchester-va-united-states) - Apple Read more
Business Analyst | *Apple* Pay - Banco Popu...
Business Analyst | Apple PayApply now " Apply now + Apply Now + Start applying with LinkedIn Start + Please wait Date:Mar 19, 2024 Location: San Juan-Cupey, PR Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.