This chapter describes how to work with some of the basic objects provided in the Foundation framework. These include numbers, strings, and collections, which refer 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 125 header files are available under OS X. As a convenience, you can simply use the following import:
Foundation.h file imports nearly all the other Foundation header files, you don’t have to worry about whether you are importing the correct header file. Xcode automatically inserts this header file ...