Objective-C

Objective-C is a general-purpose, high-level, 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 APIs, Cocoa and Cocoa Touch.

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. Generic Objective-C programs that do not use the Cocoa or Cocoa Touch libraries can also be compiled for any system supported by GCC or Clang.

Read more about Objective-C:  History, Syntax, Other Features, Library Use, Analysis of The Language