The Objective-C Language

This chapter describes the Objective-C language and discusses the principles of object-oriented programming as they're implemented in Objective-C. It covers all the basic features that the language adds to standard C. The next chapter continues the discussion by taking up more advanced and less commonly used language features.

Objective-C syntax is a superset of standard C syntax, and its compiler works for both C and Objective-C source code. The compiler recognizes Objective-C source files by a ".m" extension, just as it recognizes files containing only standard C syntax by a ".c" extension. The Objective-C language is fully compatible with ANSI standard C.

Because object-oriented programs postpone many decisions from compile time to run time, object-oriented languages depend on a run-time system for executing the compiled code. The run-time system for the Objective-C language is discussed in Chapter 5. This chapter and the next present the language, but touch on important elements of the run-time system as they're important for understanding language features. Apple has modified the GNU C compiler to compile Objective-C, and Apple provides its own run-time system.

© 2001 Apple Computer, Inc.