Objective-C is a reflective, object-oriented programming language, which adds Smalltalk-style messaging to the C programming language. Today it is used primarily on Apple's Mac OS X and iPhone OS: two environments based on, although not compliant with, the OpenStep standard. Objective-C is the primary language used for Apple's Cocoa API, and it was originally used as the main language on NeXT's NeXTSTEP OS. Generic Objective-C programs which do not make use of these libraries can also be compiled for any system supported by gcc, which includes an Objective-C compiler. History In the early 1980s, common software engineering practice was based on structured programming. Structured programming was implemented in order to help "break down" programs into smaller parts, primarily to make them easier to work on as they grew increasingly large. However, as the problems being solved grew in size, structured programming became less useful as more and more procedures had to be written, leading to complex control structures and a low level of code reuse. Many saw object-oriented programming as a potential solution to the problem. In fact, Smalltalk had already addressed many of these engineering issues; some of the most complex systems in the world were Smalltalk environments. On the downside, Smalltalk used a virtual machine. The virtual machine interpreted an object memory called an image, containing all development tools. The Smalltalk image was very large and tended to require huge amounts of memory for the time. The virtual machine also ran very slowly, partly due to the lack of useful hardware VM/container support. Objective-C was created primarily by Brad Cox and Tom Love in the early 1980s at their company Stepstone. Both had been introduced to Smalltalk while at ITT Corporation’s Programming Technology Center in 1981. Cox had become interested in the problems of true reusability in software design and programming. He realized that a language like Smalltalk would be invaluable in building development environments for system developers at ITT. Cox began by modifying the C compiler to add some of the capabilities of Smalltalk. He soon had a working implementation of an object-oriented extension to the C language, which he called "OOPC" for Object-Oriented Programming in C. Meanwhile, Love was hired by Schlumberger Research in 1982 and had the opportunity to acquire the first commercial copy of Smalltalk-80, which further influenced development of their brainchild. In order to demonstrate that real progress could be made, Cox showed that making interchangeable software components really needed only a few practical changes to existing tools. Specifically, they needed to support objects in a flexible manner, come supplied with a usable set of libraries, and allow for the code (and any resources needed by the code) to be bundled into a single cross-platform format. Love and Cox eventually formed a new venture, Productivity Products International (PPI), to commercialize their product, which coupled an Objective-C compiler with class libraries. In 1986, Cox published the main description of Objective-C in its original form in the book Object-Oriented Programming, An Evolutionary Approach. Although he was careful to point out that there is more to the problem of reusability than just the language, Objective-C often found itself compared feature for feature with other languages.
