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

Bookends 12.5.8 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Access the power of Bookends directly from Mellel, Nisus Writer Pro, or MS Word (... Read more
Chromium 44.0.2403.125 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 44.0.2403.125: This release contains a number... Read more
iMazing 1.2.2 - Complete iOS device mana...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
Audio Hijack 3.2.0 - Record and enhance...
Audio Hijack (was Audio Hijack Pro) drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio... Read more
FontExplorer X Pro 5.0.1 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
Calcbot 1.0.2 - Intelligent calculator a...
Calcbot is an intelligent calculator and unit converter for the rest of us. Featuring an easy-to-read history tape, expression view, intuitive conversion, and much more! Features History Tape -... Read more
MTR 5.0.0.1 - The Mac's oldest and...
MTR (was MacTheRipper)--the Mac's oldest and smartest DVD-backup app--is now updated to version 5.001 MTR -- the complete toolbox, not a one-trick, point-and-click extractor. MTR is intended for... Read more
LibreOffice 4.4.5.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
Adobe Lightroom 6.1.1 - Import, develop,...
Adobe Lightroom is available as part of Adobe Creative Cloud for as little as $9.99/month bundled with Photoshop CC as part of the photography package. Lightroom 6 is also available for purchase as a... Read more
File Juicer 4.41 - Extract images, video...
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. It finds and... Read more

Pac-Man Championship Edition DX has brou...
Bandai Namco has released Pac-Man Championship Edition DX on iOS and Android, which features the classic arcade gameplay that we've all grown to love. Pac-Man Championship Edition DX can be enjoyed in much shorter bursts than the arcade versions... | Read more »
Cosmonautica (Games)
Cosmonautica 1.1 Device: iOS Universal Category: Games Price: $6.99, Version: 1.1 (iTunes) Description: Cast off! Are you ready for some hilarious adventures in outer space? | Read more »
Rescue humanity from a Demon horde in An...
Angel Stone is Fincon's follow up to the massively successful Hello Hero and is out now on iOS and Android. You play as a member of The Resistance, a group of mighty human warriors who have risen up in defiance of the Demon horde threatening to... | Read more »
Gallery Doctor (Photography)
Gallery Doctor 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Free up valuable iCloud and iPhone storage with Gallery Doctor, the only iPhone cleaner that automatically identifies the... | Read more »
You Against Me (Games)
You Against Me 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: A simple game… You. Me. Claim, steal, lock, score, win! | Read more »
Yep, it's True - Angry Birds 2 is O...
The not exactly rumors were true and the birds are back. Angry Birds 2 has come to the App Store and the world will... well I suppose it'll still be the same, but now we have more bird-flinging options! [Read more] | Read more »
You Could Design Your Own Card for Chain...
If you've ever wanted to create your own item, weapon, trap, or even monster for Chainsaw Warrior: Lords of the Night, this is your chance. Auroch Digital is currently holding a contest so that fans can fight to the death (not really) to see which... | Read more »
Bitcoin Billionaire is Going Back in Tim...
If you thought you managed to buy everything there is to buy in Bitcoin Billionaire and make all the money, well you though wrong. Those of you who made it far enough might remember investing in time travel - and it looks like that investment is... | Read more »
Domino Drop (Games)
Domino Drop 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Domino Drop is a delightful new puzzle game with dominos and gravity!Learn how to play it in a minute, master it day by day.Your... | Read more »
OPERATION DRACULA (Games)
OPERATION DRACULA 1.0.1 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0.1 (iTunes) Description: 25% off launch sale!!! 'Could prove to be one of the most accurate representations of the Japanese bullet hell shmup... | Read more »

Price Scanner via MacPrices.net

11-inch MacBook Airs on sale for $100 off MSR...
Best Buy has 11-inch MacBook Airs on sale for $100 off MSRP. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary: - 11″ 1.6GHz... Read more
iPad Air 2 on sale for up to $100 off MSRP
Best Buy has iPad Air 2s on sale for up to $100 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online... Read more
Sale! 13-inch MacBook Pros on sale for $100 o...
B&H Photo has 13″ MacBook Pros on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.5GHz/500GB MacBook Pro: $999.99 save $100 - 13″ 2.7GHz/128GB Retina... Read more
Sale! Save $100 on 13-inch MacBook Airs this...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model.... Read more
Worldwide Tablet Market Decline Continues, Ap...
The worldwide tablet market declined -7.0% year-over-year in the second quarter of 2015 (2Q15) with shipments totaling 44.7 million units according to preliminary data from the International Data... Read more
TP-LINK TL-PA8030P KIT Powerline Featuring Ho...
Consumer and business networking products provider TP-LINK is now shipping its TL-PA8030P KIT AV1200 3-Port Gigabit Passthrough Powerline Starter Kit that expands your home’s network over its... Read more
Apple refurbished iPad Air 2s available for u...
The Apple Store has Apple Certified Refurbished iPad Air 2s available for up to $140 off the price of new models. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB... Read more
Updated Apple iPad Price Trackers
We’ve updated our iPad Air Price Tracker and our iPad mini Price Tracker with the latest information on prices and availability from Apple and other resellers. Read more
Apple refurbished 2014 13-inch 128GB MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ MacBook Airs available starting at $759. An Apple one-year warranty is included with each MacBook, and shipping is free: - 13″ 1.4GHz/128GB... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more

Jobs Board

Infrastructure Engineer - *Apple* /Mac - Hil...
Infrastructure Engineer - Apple /Mac Job Code: 1608 # of openings: 1 Description Our fortune 500 client is looking to hire an experienced Infrastructure Engineer to join Read more
Executive Administrative Assistant, *Apple*...
…supporting presentation development for senior leadership. * User experience with Apple hardware and software is preferred. Additional Requirements The following list Read more
*Apple* Bus Company is now hirin - Apple Bus...
Apple Bus Company is now hiring school bus drivers in the Pettis County area. Class B CDL preferred. Free training provided. No nights or weekends required. Flexible Read more
*Apple* Certified Mac Technician - Updated 6...
…and friendly, hands-on technical support to customers troubleshooting and repairing Apple /Mac products with courtesy, speed and skill. Use your problem-solving skills Read more
Infrastructure Engineer - *Apple* /Mac Envir...
…a part of a team Requires proven problem solving skills Preferred Additional Apple Certified System Administrator (ACSA) Apple Certified Technical Coordinator (ACTC) Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.