The inventor of Objective-C, Brad Cox wrote the classic Object-Oriented Programming: An Evolutionary Approach where he defines the concept of "Software-IC" for "Software Component" based systems/design/programming. The underlying C language provides the gate/block-level granular abstractions while the OO features grafted on top provides the chip-level reusability with loose coupling. This is a great mental model to have while programming large systems. The book itself is a classic on how to evolve a language.

Brad Cox's above book and Bertrand Meyer's Object-Oriented Software Construction (using the Eiffel language) were my guides to Object-Oriented Design/Programming and Software Engineering in general and i am eternally grateful to them.