- Web Graphics, Part 3: WebGL
- Web Graphics, Part 2: Scalable Vector Graphics
- Web Graphics, Part 1: The Canvas
- Introducing OpenCL
- Understanding the Cocoa Text System
- Replacing Flash with Cocoa
- Cocoa Programming Fundamentals: UNIX Tools in Cocoa
- Inside the Symbian Kernel
- IPv6: Why Bother?
- Writing a Good Set of Coding Conventions
- SCTP: Reinventing Internet Communication
- Objective-C for Java Programmers, Part 2
- Objective-C for Java Programmers, Part 1
- Exploring HTML 5
- How to Make Money with Free Software
- Objective-C Design Patterns
- Grand Central Dispatch: Exciting or Overhyped?
- Introducing HTML 5
- The State of Open Source 3D
- What Is Mac OS X?
- Snow Leopard: The Underhyped APIs
- Foundation: The Objective-C Standard Library
- Cocoa Tips: Exposing System Services
- Cocoa Tips: Don't Reimplement Standard Functionality
- Localizing Cocoa
- How Core Animation Changed Cocoa Drawing
- Using Distributed Objects in Cocoa
- Inside Modern X11 Programming
- Making JavaScript Fast, Part 2
- Security in Your Pocket: OpenBSD on ARM
- Making JavaScript Fast, Part 1
- The Failure of the GPL
- How Not To Optimize
- A Half-Way Step to Apple’s Source Code: An Interview with David Chisnall
- Advanced Flow Control for Objective-C
- Erica Sadun on the iPhone SDK, OS X, and the Computing Landscape
- From NeXTSTEP to Cocoa: Erik Buck on the Development of Cocoa and Objective-C
- Fun with the Objective-C Runtime
- Marcus Zarra and Matt Long on Core Animation
- Steve Kochan on the Evolution of Objective-C
- The Technology NeXT Gave the World
- Where the Web and the Desktop Meet: An Interview with Lee Barney
- Pandora: An Open Console
- The Future of Wireless Networking
- GNU or Linux?
- Debugging C-Family Languages
- How Small Is Your PC? The Rise of Netbooks and Other Small Form-Factor PCs
- David Chisnall's CPU Feature Wishlist
- The Dynamic Languages Renaissance
- Robert Seacord on the CERT C Secure Coding Standard
- Objective-C for C++ Programmers, Part 3
- Objective-C for C++ Programmers, Part 2
- Objective-C for C++ Programmers, Part 1
- Writing Insecure C, Part 3
- Writing Insecure C, Part 2
- Writing Insecure C, Part 1
- iRex iLiad e-Reader: Linux's Answer to the Kindle?
- How It Works: Filesystems
- How the LLVM Compiler Infrastructure Works
- How It Works: Virtual Memory
- What Is C For?
- The Future of eBooks
- Imagining an Open Network
- Understanding How Xen Approaches Device Drivers
- Examining the Legendary HURD Kernel
- Competition Among Open Source Compilers
- Inside Your OS: What is a Process Scheduler, and How Does it Work?
- Bad UI of the Week: Read This (OK/Cancel)
- The End of the Desktop Era
- The What and Why of Open IM
- A Look at the Modern X Server
- The Future of Digital Media
- The Future of Identity
- Bad UI of the Week: Ask Forgiveness, Not Permission
- Copyright Versus Free Software
- Is Computer Science Dying?
- A Brief History of Programming, Part 2
- A Brief History of Programming, Part 1
- The 700MHz Question: Will the Wireless Spectrum Auction Lead to Innovation or More of the Same?
- Bad UI of the Week: The Menu Bar
- The Dark Corners of x86
- Bad UI of the Week: The Cross-Platform User Interface
- Bad UI of the Week: The Mythical "is Like" Operator
- Bad UI of the Week: Don't Make Me Tell You Twice...
- Bad UI of the Week: Kettles and Washing Machines
- The BBC iPlayer Controversy Explained
- Bad UI of the Week: The Mitten Mouse
- Bad User Interface of the Week: File It Under “Bad”
- Bad User Interface of the Week: The DVD
- A Roundup of Free Operating Systems
- DragonFly BSD: UNIX for Clusters?
- CPU Wars, Part 3: Put Your Left ARM In
- CPU Wars, Part 2: POWER to the People
- CPU Wars, Part 1: When the Chips Are Down
- ZFS Uncovered
- Vector Programming with GCC
- Free Software Versus Open Source Software
- What Programming Languages Should You Know?
- Standardizing UNIX
- Prolog: Logic Programming for Rapid Development
- POSIX Parallel Programming, Part 3: Threads
- POSIX Parallel Programming, Part 2: Message Passing
- POSIX Parallel Programming, Part 1
- The Nokia 770 Revisited
- The Open Source Desktop Myth
- Separating Style and Content: LaTeX and Typesetting
- GNUstep: A Free Software alternative to OpenStep
- Behind the Scenes of Objective-C 2.0
- The Future of CPUs: What's After Multi-Core?
- What Makes a Good Programming Language?
- Emulation: Role-Playing for Computers
- NetBSD: Not Just for Toasters
- POSIX Asynchronous I/O
- Breaking Down GPL Version 3
- The Role of Binary Drivers in a Free OS
- Security Is a UI Problem
- Debunking the Myth of High-level Languages
- A Taste of Erlang, a Dynamic, Asynchronous Message-Passing Language
- Alternatives to LAMP
- BSD Packaging Systems
- DRM: Digital Rights or Digital Restrictions?
- Introducing OpenBSD 3.9
- The Need for Virtualization and Xen
- Making Effective Software TCO Calculations
- 10 Things I Hate About U(NIX) Revisited: Readers Speak
- Comparing Open Source Licenses: GPL vs. BSDL
- BSD: The Other Free UNIX Family
- Measuring the Effectiveness of Application Security Policies
- The Cost of Free Software
- Nokia 770 Internet Tablet Week-long Test Drive
- 10 Things I Hate About (U)NIX
- The Lure of Open Source Software: Why Consider It for Your Business?
- Cocoa Tip of the Day, 1/29/10
Don't ignore old versions of OS X.
- Cocoa Tip of the Day, 1/28/10
Exceptions should be exceptional.
- Cocoa Tip of the Day, 1/27/10
Explore the runtime system.
- Cocoa Tip of the Day, 1/26/10
Copy design patterns from Cocoa.
- Cocoa Tip of the Day, 1/25/10
Profile with Instruments.
- Cocoa Tip of the Day, 1/22/10
Expose system services.
- Cocoa Tip of the Day, 1/21/10
Always read the release notes for new OS X versions.
- Cocoa Tip of the Day, 1/20/10
Broadcast events with notifications.
- Cocoa Tip of the Day, 1/19/10
Port your code with GNUstep.
- Cocoa Tip of the Day, 1/18/10
Use CoreAnimation for caching.
- Cocoa Tip of the Day, 1/15/10
Don't recreate standard features.
- Cocoa Tip of the Day, 1/14/10
Don't forget NSCell.
- Cocoa Tip of the Day, 1/13/10
Plan for code reuse.
- Cocoa Tip of the Day, 1/12/10
Remember the C in Objective-C.
- Cocoa Tip of the Day, 1/11/10
Separate interfaces and implementations.
- Cocoa Tip of the Day, 1/8/10
Think about localisation early.
- Cocoa Tip of the Day, 1/7/10
Read the Human Interface Guidelines.
- Cocoa Tip of the Day, 1/6/10
Don't optimise yet.
- Cocoa Tip of the Day, 1/5/10
Put controllers in nib files.
- Cocoa Tip of the Day, 1/4/10
Don't write code.
- Cocoa Tip of the Day, 1/1/10
Use Distributed Objects for local network communication.
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Programming in Objective-C 2.0, 2nd Edition
When Apple introduced OS X, C or C++ was supported through Carbon and Objective-C or Java via the Cocoa APIs. With the 64-bit switch, Carbon started to go away, and the Java interface to Cocoa hasn't been updated for several years. When the iPhone was introduced, no other languages were supported for third-party developers. Objective-C is something of an obscure language. It was created in the 1980s and only really pushed commercially by NeXT. So what makes Apple love it so much for OS X development?
Learning Objective-C is very easy. If you already know C, Objective-C is just one extra syntactic structure and a handful of keywords. Being easy to learn is nice, but it's not enough. Learning any language (with the possible exception of Intercal or C++) is only a tiny fraction of the time you spend using that language. If it isn't easy to write the kind of code you want in that language, you'd be better off spending a few days learning a different language. In this article, we'll take a look at a technique that's very easy for languages in the same family as Objective-C, and much harder in others.
Objects and Messages
There's some debate over which language was the first true object-oriented language. The first to be called "object-oriented" was Smalltalk, in 1971. Many of the constructs in this language were superficially similar to those in Simula, which had appeared a few years earlier.
Objective-C is an example of the Smalltalk school of object-oriented programming. The object-oriented model for Smalltalk, proposed by Alan Kay, was that you had simple computers that communicated by passing messages. An important thing to note here is that classes are nowhere in the description. Classes are not required for object-oriented programming in the Smalltalk school. In Smalltalk, a class is just a kind of object that acts as a factory for others and handles method lookup. Newer languages in the Smalltalk family, such as Self and JavaScript, have no classes.
In the other branch of the object-oriented family, classes are very important. C++ was originally called "C with classes" and was intended to provide C with Simula-style support for abstract data types — very different from the Smalltalk model.
This distinction is very important because it means that, in the Smalltalk family, flow control is entirely under the developer's control. In Smalltalk, sending messages was the only way of moving control around your program. If you wanted a conditional statement, you sent an ifTrue: message to a Boolean object with a block (closure) object as the argument. Objective-C, inheriting static flow-control constructs from C, keeps a lot of the flexibility of Smalltalk.
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