Chapter 15. Numbers, Strings, and Collections

This chapter describes how to work with some of the basic objects provided in the Foundation framework. These include numbers; strings; and collections, which refers to the capability to work with groups of objects in the form of arrays, dictionaries, and sets.

The Foundation framework contains a plethora of classes, methods, and functions for you to use. Approximately 100 header files are available on the Mac, and 70 are available as part of GNUStep that you can import into your program. As a convenience, you can simply use the following import:

#import <Foundation/Foundation.h>

Then you don't have to worry about whether you are importing the correct header file. This header file is automatically imported into your program by Project Builder when you create a Foundation Tool, as described previously in Chapter 14, "Introduction to the Foundation Framework."

Because the Foundation.h file imports virtually all the other Foundation header files, using this statement can add a significant amount of time to your compiles. You can, however, avoid this extra time by using precompiled headers. These are files that have been preprocessed by the compiler. By default, all Project Builder projects benefit from precompiled headers. In this chapter, you'll use the specific header files for each object you use. This will help you become familiar with what's contained in each header file.