TweetFollow Us on Twitter

May 01 ADC Direct Volume Number: 17 (2001)
Issue Number: 5
Column Tag: ADC Direct

Cocoa: A New Flavor to Mac OS Development

By Godfrey DiGiorgi

Mac OS X integrates five separate application runtime environments—Carbon, Cocoa, Classic, Java, and BSD—into one seamless whole, providing developers with many options. This article introduces Cocoa, an important development technology used by Apple, to develop many of the applications that ship with Mac OS X. Cocoa constitutes a new, highly efficient way for developers to create new products for Mac OS X.

A Brief Overview

Cocoa is an object-oriented application framework and runtime environment—a set of software components used to construct applications that run on Mac OS X. Think of Cocoa as a large set of reusable application building blocks that can be used as delivered or extended for your specific needs.

Cocoa is based on OpenStep, an object-oriented technology that was originally introduced in 1987 as NeXTSTEP and has been refined through many iterations. Consequently, Cocoa is mature technology based on a design years ahead of other object-oriented frameworks.

Like any software library, Cocoa has a learning curve for newcomers, but it is not an overly difficult one and productivity comes quickly. The Cocoa framework delivers a great deal of fundamental application functionality so you can spend the majority of your energy working on application features rather than managing the more tedious parts of system interface and user experience implementation.

The primary implementation language used in Cocoa is Objective-C, a superset of ANSI C with specific language features added to allow for object-oriented programming. The language extensions in Objective-C are compact and easy to learn. Cocoa applications make extensive use of the classes and methods in Cocoa component libraries. However, because of Objective-C’s compatibility with ANSI C, they can also make use of core functionality contained in traditional C and C++ libraries brought from other application environments.

Features and Development Scope

Cocoa is a peer to the Carbon and Java application development environments in Mac OS X. Cocoa supports all Mac OS X application service features. For example, Cocoa applications can access the Mac OS X native imaging and printing model, multimedia standards QuickTime and OpenGL, and Internet and BSD services, too. Localization and Internationalization are also well supported by Cocoa. The separation of user interface elements from executable code allows you to package your applications for different locales easily, with no code changes. All Cocoa text drawing utilizes the Unicode standards. The text and font systems are particularly flexible and allow you to use sophisticated word processing features with little effort.

An important development advantage that Cocoa offers is the capability to develop programs quickly and easily by assembling reusable components. With reusable components, developers can not only create applications, but also produce:

  • Frameworks (sophisticated library structures)
  • Bundles of executable code and associated resources which can be loaded and executed dynamically
  • Collections of custom user-interface objects

These capabilities support the easy creation and distribution of application plug-ins and extensions.

Tools and Resources

Apple put the tools for Cocoa development directly into the hands of developers by including them in every Mac OS X package on the Mac OS X Developer Tools CD. Just install the Developer.pkg file and the complete Apple tool suite is installed and ready for use. This installation includes the Project Builder Integrated Development Environment, Interface Builder—the application for designing and testing user interfaces and establishing the connections between objects and actions—as well as all the interface files, debugging and performance tools, and full online documentation.

Once you have installed the Developer.pkg, open a Finder window and you will find the /Developer directory on your system volume. Inside this directory, in /Applications, are the Project Builder and Interface Builder applications along with many other tools. In /Developer/Documentation are folders containing PDF and HTML help and documentation files for Cocoa and the developer tools.

Finally, in /Developer/Examples are /AppKit and /Foundation sample code folders with Cocoa applications for you to learn from and even reuse for your own project.

Taking Apart the Technology

Cocoa is comprised of two object-oriented frameworks: Foundation (Foundation.framework) and Application Kit (AppKit.framework). The Foundation classes provide the low-level objects and functionality that form the basis of the Cocoa environment. The classes in Application Kit provide the functionality users see in the user interface, which respond to system events such as mouse clicks and key presses. The Application Kit is layered directly on Foundation. Here is a brief look at the functionality contained in each of these frameworks.

The Foundation Framework is designed to provide a set of basic utility classes, introduce consistent conventions for paradigms (such as memory management) support Unicode strings, object persistence, and file management. Foundation includes:

  • the root object class
  • classes representing basic data types such as strings and byte arrays
  • collection classes for storing other objects
  • classes representing system information such as dates and
  • classes representing communication ports

Several paradigms are also defined in Foundation to help avoid confusion in common situations and introduce consistency across class hierarchies. This is done with some standard policies, like the one used for object ownership (answering questions such as: “Who is responsible for disposing of an object?”), and also with abstract classes which enumerate over collections. These paradigms reduce special and exceptional cases in code management and allow reuse of the same mechanisms with various kinds of objects. All together, these paradigms improve development efficiency and productivity.

The Application Kit framework contains all the objects needed to implement the graphical, event-driven user interface: windows, panels, buttons, menus, scrollers, text fields, etc. The Application Kit handles all the details for you as it efficiently draws on the screen, communicates with hardware devices and screen buffers, clears areas of the screen before drawing, and clips views. There are over a hundred classes in the Application Kit, so it might seem a steep learning curve, but many of the Application Kit classes are support classes that are only used indirectly.

For a detailed listing of the Foundation and Application Kit object classes, see the documentation in: /Developer/Documentation/Cocoa/CocoaTopics.html.

Object-Oriented Programming

For traditional Mac programmers, Cocoa development represents a paradigm shift—from a procedural to an object-oriented development model. The “free” functionality found in the Foundation and Application Kit frameworks helps Mac programmers realize the benefits of this easy, natural way to develop applications.

Object-oriented programming allows the construction of complex applications through assembling small, well-tested, reusable modules called objects. This provides three simple advantages:

1. Greater reliability by breaking complex implementations into smaller, easily testable components.

2. Easier maintainability due to the small, modular nature of objects. (This small size allows one to fix bugs found in testing more easily.)

3. Greater productivity through reuse. The ability to use an existing class over and over again means less redundant work. When you need to extend the functionality of a particular class to meet a specific need, you can do so easily through the use of a mechanism called inheritance. You only need to code the specific functionality you are adding to a class, the rest of the object’s behavior is inherited from the preexisting parent class.

For more information, see the documentation in: /Developer/Documentation/Cocoa/ObjectiveC/index.html.

Fundamentals of Cocoa Programming

Cocoa is a rich object-oriented environment. Object-oriented programming makes heavy use of patterns to simplify design and implementation of complex systems. The three most essential patterns to learn when starting are:

1. Model-View-Controller (MVC) - MVC defines three types of objects in an application: model, view, and controller. Model objects hold data and define the logic that manipulates that data. View objects represent user interface elements (a window, for example). Controller objects act as mediators between model objects and view objects. This mediation role allows view objects to be free from the programmatic interfaces of models and vice-versa.

2. Target/Action - This is part of the mechanism by which user interface controls respond to user actions. When a user clicks a user interface control, the control sends an action message to the target object.

3. Delegation - Delegation lets you modify an object’s behavior without creating a custom subclass. A delegate acts on behalf of another object. When a delegate receives a message (from a window, a view, etc.), the sender of the message is allowing the delegate to influence its behavior and aid in decision-making (such as: “Should I allow the user to close me?”).

Cocoa leverages the dynamic binding and object introspection capabilities of Objective-C and Java by allowing delegate objects to implement just the functionality they want to influence. At runtime, the delegating objects can query their delegates to see what methods have actually been implemented. This saves you from having to subclass some specific parent class (that has all the default implementations), helping to preserve your application’s unique class hierarchy.

These patterns are discussed at length in Inside Cocoa: Object-Oriented Programming and the Objective C-Language and in other parts of the Cocoa documentation.

Another integral part of Cocoa programming practice is the use of Interface Builder. Interface Builder is a design tool, allowing you to easily define and test a user interface. It is also used with Cocoa to define object classes and “wire” the connections of targets and actions. Interface Builder creates ‘nib’ files, which are a static representation of objects and their relationships. These nib files are efficiently loaded as needed at runtime. Interface Builder is closely tied to the Project Builder IDE for a smoothly integrated development experience. For more information on Interface Builder and Project Builder, see the documentation available in: /Developer/Documentation/DeveloperTools

as well as on the Web at:

http://developer.apple.com/tools/projectbuilder/

http://developer.apple.com/tools/interfacebuilder/


Project Builder Tips and Tricks

  • You can use Build Styles instead of duplicate targets for many things that would require duplicate targets in other environments.
  • All text fields in Project Builder that contain file paths support path completion (completion is bound to the F5 key by default).
  • Any place where single clicking an item loads that item into the built-in editor, double-clicking will open the item in a separate window. This includes the files list, bookmarks, targets, build results, find results, etc.

Language Support

Cocoa is implemented in Objective-C. As a superset of ANSI C with special syntax and runtime extensions, Objective-C lets you use object-oriented programming techniques while leveraging as much of the use and knowledge of standard ANSI C as possible.

Java can also be used to implement Cocoa applications through the use of the Java API versions of the Foundation and Application Kit frameworks. See the Foundation and Application Kit reference locations.

Where to Go for More Information

In Summary

The demand for Mac OS X applications is huge and Cocoa can help you bring new products to market quickly, using the full power of Mac OS X development tools and object-oriented methodology to facilitate your work.

Whatever Mac OS X development path you choose, Apple is eager to assist you. For the latest Mac OS X news and information, visit the Apple Developer Connection web site at:
http://developer.apple.com/macosx


New Mac OS X Releases

The following software is available from the Download Software area of the ADC Member Site at:
http://connect.apple.com/

Developer Documentation

  • O'Reilly and Apple Collaborate on Mac OS X Book Series
    O'Reilly and Associates, has announced plans to publish a series of books about Mac OS X development. The books in this series have been technically reviewed by Apple engineers and are recommended by the Apple Developer Connection. The first Mac OS X titles, Learning Carbon and Learning Cocoa, are available this May. In addition, the O'Reilly Network has established the Mac DevCenter, a web forum for development news and articles.
  • Apple Technical Publications
    Over thirty new and updated documents have been added in the last month to help developers with successful Mac OS X application and peripheral development at:
    http://developer.apple.com/techpubs/

TN2015 - Locating Application Support Files Under Mac OS X

TN2014 - Insights on OpenGL

TN2013 - The 'plst' Resource

TN2012 - Building QuickTime Components for Mac OS X

QA1019 - Can't attach during two-machine debugging with GDB

QA1018 - Using AppleScript to send an email with an attachment

QA1013 - Mac OS X and root access


SC - More than thirty new Mac OS X code samples were posted to the ADC web site since the last issue. Please visit the URL below for a complete list of sample code. http://developer.apple.com/samplecode/


"Built for Mac OS X" Artwork now Available


Now that customers have Mac OS X in their hands, they'll be looking for great products to run on it. Tell the world that your product runs on Mac OS X by displaying the "Built for Mac OS X" badge on your product's packaging. The artwork, licensing requirements, and usage guidelines are available on the ADC Software Licensing web site.
http://developer.apple.com/mkt/swl/agreements.html#macosx

Upcoming Seminars and Events

For more information on Apple developer events please visit the developer Events page at:
http://developer.apple.com/events/

Training and Seminars

  • Apple iServices: Cocoa Development Classes This five-day course provides comprehensive, hands-on training using real-world examples. With the skills acquired in this course, developers can build full-featured applications using the most advanced software environment on Mac OS X.
    http://www.apple.com/iservices/technicaltraining/cocoadev.html
  • Programming With Cocoa
    Taught by Aaron Hillegass at the Big Nerd Ranch, Ashville, NC and Atlanta, GA. Five-day classes are taught on developing web-based and Mac OS X applications.
    http://www.bignerdranch.com/when.html

Developer Related Conferences

  • Worldwide Developers Conference (WWDC) 2001, San Jose, CA
    May 21-25
    Register now for Apple's Worldwide Developers Conference 2001, which takes place in San Jose, California from May 21-25. ADC Premier members receive one free pass to the conference. For schedules and other details check out:
    http://www.apple.com/developer/wwdc2001/
  • MacHack Conference, Dearborn, MI
    June 21-23
    MacHack, in its sixteenth year, remains centered around cutting edge software development. MacHack's uniqueness derives from the informal feel and the LIVE coding that occurs around-the-clock during the conference.
    http://www.machack.com/

Did You Know?

Learning Cocoa—and Mastering It


To programmers new to Cocoa--Apple's powerful object-oriented application environment--the road to mastery is a challenging yet rewarding one. Although there are many new things to learn, once you become comfortable with Cocoa, your programming productivity will take off. Guaranteed.

To help you in your Cocoa apprenticeship, Apple provides two great sources of technical information. The first is the book Learning Cocoa, published by O'Reilly. Written by insiders at Apple Computer, Learning Cocoa mixes conceptual overviews with hands-on tutorials to give you a crash course in Cocoa application development. The idea is that learning Cocoa should not be just a matter of reading, but doing. Learning Cocoa guides you through the creation of several applications, each more complex than the one before. By the end of the book, you'll be prepared to take on serious application development on your own. Look forLearning Cocoa in technical bookstores near you; you can also purchase it direct from O'Reilly at:
http://www.oreilly.com/catalog/learncocoa/

The second source of information on Cocoa is Apple's own technical publications, especially its Cocoa programming topics. The programming topics are a hierarchically organized collection of information nodes on such topics as implementing undo, custom drawing, and managing text. Each node brings together (in an HTML frame set) the conceptual, procedural, and reference documentation that illuminates a single programming task. In addition to documentation, a programming topic includes links to example projects, technical notes, and other sources of information. If you have the Developer package installed, you can access the Cocoa programming topics through the Developer Help Center. You can also view them on the ADC Developer Documentation web site at:
http://developer.apple.com/techpubs/macosx/Cocoa/CocoaTopics.html


Godfrey DiGiorgi is Technology Manager for Development Tools & Cocoa in Apple Worldwide Developer Relations. He’s been associated with Macintosh development for more years than he’d care to admit. He can be reached at ramarren@apple.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Bookends 12.8 - Reference management and...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Apple iTunes 12.6 - Play Apple Music and...
Apple iTunes lets you organize and stream Apple Music, download and watch video and listen to Podcasts. It can automatically download new music, app, and book purchases across all your devices and... Read more
Default Folder X 5.1.4 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click on... Read more
Amazon Chime 4.1.5587 - Amazon-based com...
Amazon Chime is a communications service that transforms online meetings with a secure, easy-to-use application that you can trust. Amazon Chime works seamlessly across your devices so that you can... Read more
CrossOver 16.2 - Run Windows apps on you...
CrossOver can get your Windows productivity applications and PC games up and running on your Mac quickly and easily. CrossOver runs the Windows software that you need on Mac at home, in the office,... Read more
Adobe Creative Cloud 4.0.0.185 - Access...
Adobe Creative Cloud costs $19.99/month for a single app, or $49.99/month for the entire suite. Introducing Adobe Creative Cloud desktop applications, including Adobe Photoshop CC and Illustrator CC... Read more
MegaSeg 6.0.2 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
Bookends 12.8 - Reference management and...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Adobe Creative Cloud 4.0.0.185 - Access...
Adobe Creative Cloud costs $19.99/month for a single app, or $49.99/month for the entire suite. Introducing Adobe Creative Cloud desktop applications, including Adobe Photoshop CC and Illustrator CC... Read more
Default Folder X 5.1.4 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click on... Read more

The best new games we played this week
It's been quite the week, but now that all of that business is out of the way, it's time to hunker down with some of the excellent games that were released over the past few days. There's a fair few to help you relax in your down time or if you're... | Read more »
Orphan Black: The Game (Games)
Orphan Black: The Game 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Dive into a dark and twisted puzzle-adventure that retells the pivotal events of Orphan Black. | Read more »
The Elder Scrolls: Legends is now availa...
| Read more »
Ticket to Earth beginner's guide: H...
Robot Circus launched Ticket to Earth as part of the App Store's indie games event last week. If you're not quite digging the space operatics Mass Effect: Andromeda is serving up, you'll be pleased to know that there's a surprising alternative on... | Read more »
Leap to victory in Nexx Studios new plat...
You’re always a hop, skip, and a jump away from a fiery death in Temple Jump, a new platformer-cum-endless runner from Nexx Studio. It’s out now on both iOS and Android if you’re an adventurer seeking treasure in a crumbling, pixel-laden temple. | Read more »
Failbetter Games details changes coming...
Sunless Sea, Failbetter Games' dark and gloomy sea explorer, sets sail for the iPad tomorrow. Ahead of the game's launch, Failbetter took to Twitter to discuss what will be different in the mobile version of the game. Many of the changes make... | Read more »
Splish, splash! The Pokémon GO Water Fes...
Niantic is back with a new festival for dedicated Pokémon GO collectors. The Water Festival officially kicks off today at 1 P.M. PDT and runs through March 29. Magikarp, Squirtle, Totodile, and their assorted evolved forms will be appearing at... | Read more »
Death Road to Canada (Games)
Death Road to Canada 1.0 Device: iOS Universal Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: Get it now at the low launch price! Price will go up a dollar every major update. Update news at the bottom of this... | Read more »
Bean's Quest Beginner's Guide:...
Bean's Quest is a new take on both the classic platformer and the endless runner, and it's free on the App Store for the time being. Instead of running constantly, you can't stop jumping. That adds a surprising new level of challenge to the game... | Read more »
How to rake in the cash in Bit City
Our last Bit City guide covered the basics. Now it's time to get into some of the more advanced techniques. In the later cities, cash flow becomes much more difficult, so you'll want to develop some strategies if you want to complete each level.... | Read more »

Price Scanner via MacPrices.net

SSD Speeder RAM Disk SSD Life Extender App Fo...
Fehraltorf, Switzerland based B-Eng has announced they are making their SSD Speeder app for macOS publicly available for purchase on their website. SSD Speeder is a RAM disk utility that prevents... Read more
iPhone Scores Highest Overall in Smartphone D...
Customer satisfaction is much higher among smartphone owners who use their device to operate other connected home services such as smart thermostats and smart appliances, according to the J.D. Power... Read more
Swipe CRM Free Photo-Centric CRM Sales DEal C...
Swipe CRM LLC has introduced Swipe CRM: Visual Sales 1.0 for iPad, an app for creating, managing, and sharing visually stunning sales deals. Swipe CRM is targeted to small-and-medium creative... Read more
13-inch 2.0GHz Apple MacBook Pros on sale for...
B&H has the non-Touch Bar 13″ 2.0GHz MacBook Pros in stock today and on sale for $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (... Read more
15-inch Touch Bar MacBook Pros on sale for up...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more
Apple’s iPhone 6s Tops Best-Selling Smartphon...
In terms of shipments, the iPhone 6s from Apple bested all competitors for sales in 2016, according to new analysis from IHS Markit, a world leader in critical information, analytics and solutions.... Read more
Logitech Rugged Combo Protective iPad Case an...
Logitech has announced its Logitech Rugged Combo, Logitech Rugged Case, and Logitech Add-on Keyboard for Rugged Case for Apple’s new, more affordable $329 9.7-inch iPad, a complete solution designed... Read more
T-Mobile To Offer iPhone 7 and iPhone 7 Plus...
T-Mobile has announced it will offer iPhone 7 and iPhone 7 Plus (PRODUCT)RED Special Edition in a vibrant red aluminum finish. The introduction of this special edition iPhone celebrates Apple’s 10... Read more
9-inch 128GB iPad Pros on sale for $50-$70 of...
B&H Photo has 9.7″ 128GB Apple WiFi iPad Pros on sale for up to $70 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 9″ Space Gray 128GB WiFi iPad Pro: $649 $50... Read more
27-inch iMacs on sale for up to $200 off MSRP...
B&H Photo has 27″ Apple iMacs on sale for up to $200 off MSRP, each including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2099 $200 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $... Read more

Jobs Board

*Apple* Retail - Multiple Positions- Chicago...
SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Fulltime aan de slag als shopmanager in een h...
Ben jij helemaal gek van Apple -producten en vind je het helemaal super om fulltime shopmanager te zijn in een jonge en hippe elektronicazaak? Wil jij werken in Read more
Starte Dein Karriere-Abenteuer in den Hauptst...
…mehrsprachigen Teams betreust Du Kunden von bekannten globale Marken wie Apple , Mercedes, Facebook, Expedia, und vielen anderen! Funktion Du wolltest schon Read more
*Apple* macOS Systems Integration Administra...
…most exceptional support available in the industry. SCI is seeking an Junior Apple macOS systems integration administrator that will be responsible for providing 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.