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What Is Objective-C?
Objective-C is a "simple computer language designed to enable sophisticated object-oriented programming. Objective-C is defined as a small but powerful set of extensions to the standard ANSI C language." Created to provide the C programming language full object-oriented programming features in a simple way, Objective-C is the primary language from which iPhone and iPad applications are built.
Where Did Objective-C Come From?
Objective-C was originally created by Brad Cox and Tom Love in the early 1980s while they worked at their company called Stepstone. They had gotten familiar with Smalltalk while working at ITT Corporation’s Programming Technology Center in 1981. Cox understood that a language such as Smalltalk could be very useful when creating development environments, so he began modifying the C compiler, adding some of the features of Smalltalk. This eventually became a working implementation of an object-oriented extension to the C language. At the time it was refered to as "OOPC" for "Object-Oriented Programming in C".
What Type of IDE Do I Need To Program in Objective-C?
The Xcode IDE is actually made up of windows that are used to develop apps using the Xcode application itself. These windows include a project window, text editor window, Documentation window and more.
Interface Builder is a graphical editor that is used to design all the aspects of your app's graphical user interface. Any time you make changes within Interface Builder, the changes are reflected in Xcode.
Do I Have To Have a Mac to Program in Objective-C?
In order to use the iPhone Software Developer's Kit (SDK) 4, you must be using an Intel-based Mac running Mac OS X Snow Leopard or later--thus far there is no Windows version of the SDK. That said, there are many tools which can be used to create iPhone and iPad apps without the use of the iPhone SDK 4 or a Mac.
Rhodes is an open source framework which enables developers to create native apps for the iPhone, as well as Windows Mobile, BlackBerry, Symbian and Android. The apps that are created using Rhodes are true native apps which are able to take advantage of the iPhone's capabilities (GPS, PIM contacts, camera, etc.). One advantage of using Rhodes is that the source code can be compiled to run on all major smartphone devices.
Zimusof's DragonFireSDK allows developers to use C and C++ to develop applications using Visual Studio or Visual Studio Express. Zimusof is responsible for packaging applications and handling developer submissions to Apple's App Store on behalf of its customers. Developers submit their apps to Zimusoft after development and testing on their own Windows PCs. Pricing for DragonFireSDK is $99 and includes one iTunes App bundling, with additional bundles available for $10 each.
There is also an Objective-C compiler for .NET that is available via Google Code.
How Does Objective-C Differ from C?
Objective-C has a different approach to extending C than does C++. C++ programming supports some aspects of object-oriented programming, generic programming and metaprogramming. It also features a large standard library that includes some container classes.
While Objective-C does add object-oriented programming, dynamic typing and reflection to C, it doesn't include a standard library, although it is usually utilized with an OpenStep-like library (OPENSTEP, Cocoa, or GNUstep), and these provide the functionality that C++’s standard library provides. An Objective-C container class can hold any object type, so some of C++'s container classes are not required.
Objective-C provides runtime support reflective features to C, while C++ programming only adds a small amount of runtime support to C. Objective-C enables an object to be queried about its own properties, while C++ programming cannot do this without the use of external libraries.
Another difference is that while Objective-C and C++ both employ a mix of run-time decisions and compile-time decisions, Objective-C is more geared toward the former and C++ programming more towards the latter.
More Objective-C Resources
We've put together a list of resources for developers who are interested in working with Objective-C. While not exhaustive, these resources can help to get you started in the world of Objective-C.
- Introduction to The Objective-C Programming Language - A detailed introduction to object-oriented programming in the context of the Objective-C programming language.
- Objective-C Beginner's Guide - Beginner's guide to Objective-C with practical coding examples that contrast Objective-C to other OOP languages like Java and C++.
- From C++ to Objective-C - I have tried to gather in this document a lot of C++ and Objective-C concepts, to show how to switch from one to another and understand the Objective-C paradigms.
- Object Oriented Programming in Objective-C - These documents provide a brief introduction to Object Oriented Programming in the Objective-C language.
- GCC, the GNU Compiler Collection - The GNU Compiler Collection includes front ends for C, C++, Objective-C, Fortran, Java, and Ada, as well as libraries for these languages.
- W3Kit 2.2 - An object-oriented toolkit for building interactive World Wide Web applications.
- Learn Cocoa - Featured tutorials from Cocoa Dev Central.
- Basic iPhone UI Elements
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- Special Report: The Definitive Guide to Windows Phone 7