Abstract:
1. Objective-C is based on SmallTalk-80, vs Simula, adopted by C++
2. Objective-C is a 'strict superset' of C
3. Objective-C model of OOP is based on Message Passing to object.
Detail:
Objective-C 1980
Object-Oriented Pre-Compiler 1982
Commercial version 1986 coupled an Objective-C compiler with class libraries
GCC compiler of Objective-C 1988 extended a GCC compiler of Objective-C
GNU Objective-C runtime 1992
Clang compiler of Objective-C 2009
Swift 2014 characterized as "Objective-C without the C"