Interview of Erik Buck on the Development of Cocoa and Objective-C From NeXTSTEP to Cocoa
Object-oriented programming languages fall into two major categories: those inspired by Simula and those inspired by Smalltalk.
C++ is a language that grafts Simula-style object orientation onto the C programming language while simultaneously trying to improve C.
Objective-C is a language that grafts Smalltalk style message sending onto C while preserving the base C language unchanged.
... Microsoft's C# .NET Framework is becoming very Cocoa like. Microsoft has finally embraced the Model View Controller design pattern that is ubiquitous in Cocoa. The C# language is evolving to be closer in concept to Objective-C.
(In Objective-C) Network distributed messages use identical syntax to local messages.
The Gang of Four frequently cite examples of their patterns not only in Smalltalk but in NeXTstep.... the Objective-C language makes many of the original Gang of Four design patterns trivial or unnecessary.