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Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. It is the main programming language used by Apple for the OS X and iOS operating systems, and their respective application programming interfaces (APIs), Cocoa and Cocoa Touch. The programming language Objective-C was originally developed in the early 1980s. It was selected as the main language used by NeXT for its NeXTSTEP operating system, from which OS X and iOS are derived. Portable Objective-C programs that do not use the Cocoa or Cocoa Touch libraries, or those using parts that may be ported or reimplemented for other systems, can also be compiled for any system supported by GCC or Clang. Objective-C source code 'implementation' program files usually have .m filename extensions, while Objective-C 'header/interface' files have .h extensions, the same as C header files. Objective-C++ files are denoted with a .mm file extension. ==History== 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. The earliest work on Objective-C traces back to around that time.〔 〕 Cox was intrigued by 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. However, he and Tom Love also recognized that backward compatibility with C was critically important in ITT's telecom engineering milieu.〔 〕 Cox began writing a pre-processor for C 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 Pre-Compiler.〔 〕 Love was hired by Schlumberger Research in 1982 and had the opportunity to acquire the first commercial copy of Smalltalk-80, which further influenced the 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Objective-C」の詳細全文を読む スポンサード リンク
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