Ĭox began writing a pre-processor for C to add some of the abilities of Smalltalk. However, he and Tom Love also recognized that backward compatibility with C was critically important in ITT's telecom engineering milieu. He realized that a language like Smalltalk would be invaluable in building development environments for system developers at ITT. Cox was intrigued by problems of true reusability in software design and programming.

The earliest work on Objective-C traces back to around that time. Leading up to the creation of their company, both had been introduced to Smalltalk while at ITT Corporation's Programming Technology Center in 1981. Objective-C was created primarily by Brad Cox and Tom Love in the early 1980s at their company Productivity Products International (PPI). h extensions, the same as C header files. m filename extensions, while Objective-C 'header/interface' files have. Objective-C source code 'messaging/implementation' program files usually have. Objective-C programs developed for non-Apple operating systems or that are not dependent on Apple's APIs may also be compiled for any platform supported by GNU GCC or LLVM/ Clang. Due to Apple macOS’s direct lineage from NeXTSTEP, Objective-C was the standard programming language used, supported, and promoted by Apple for developing macOS and iOS applications (via their respective APIs, Cocoa and Cocoa Touch) until the introduction of the Swift programming language in 2014. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTSTEP operating system. Objective-C is a high-level general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Groovy, Java, Nu, Objective-J, TOM, Swift

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