Objective-CA language combining C with Smalltalk-style object messaging — used for macOS and iOS before Swift. adds object message:arg syntax on top of C — the language behind NeXTSTEP, macOSApple's desktop operating system — runs on Mac hardware with Unix foundations and the Cocoa UI framework., and iOSApple's mobile operating system — runs iPhone and iPad with a sandboxed app ecosystem. until SwiftApple's language for iOS, macOS, and server apps — designed for safety and performance.. Cocoa/UIKit APIs are Objective-CA language combining C with Smalltalk-style object messaging — used for macOS and iOS before Swift. (or bridged to SwiftApple's language for iOS, macOS, and server apps — designed for safety and performance.). Developers used it for iPhoneApple's smartphone line — touch-first mobile computing and the App Store ecosystem since 2007. apps, Mac desktop software, and NeXT workstations through Apple's 2010s transition.

Objective-CA language combining C with Smalltalk-style object messaging — used for macOS and iOS before Swift. powered Apple's platform for two decades and bridged C systems code with OOPObject-oriented programming — organizing code around objects that combine data and behavior..

It showed how to layer dynamic object messaging on C without a new runtime virtual machineSoftware that emulates a computer — often runs one OS inside another for isolation or portability. — a model SwiftApple's language for iOS, macOS, and server apps — designed for safety and performance. later refined.