This appendix summarizes the Objective-C language in a format suitable for quick reference. It is not intended to be a complete definition of the language, but rather a more informal description of its features. You should thoroughly read the material in this appendix after you have completed the text. Doing so will not only reinforce the material you learned, but also provide you with a better global understanding of Objective-C.
This summary is based on the ANSI C99 (ISO/IEC 9899:1999) standard with Objective-C 2.0 language extensions. As of this writing, the latest version of the GNU gcc compiler used on my Mac OS X v10.5.5 system is version 4.0.1.