Most Cocoa classes begin with NS since they were initiated under NeXTStep.
Objective-C is a superset of the C language.
An interface is where you define the attributes and operations of class.
An Objective-C method is just a C function with two arguments always present at the beginning.
Is exactly equivalent to the C function
CoreFoundation is written in C while Foundation is written in Objective-C.
- Cocoa Touch layer
- Media layer
- Core services layer
- Core OS layer