The Macintosh and iPhone are general-purpose computing platforms. You can program them in any number of languages from Fortran to Tcl, Ruby to Nu, C to Java. However, the primary application programming interfaces (APIs) from Apple are designed to work in plain C and Objective-C. The Unix API is C-based, while Cocoa and Cocoa Touch are Objective-C based.
A solid grounding in C and Objective-C, though, is very important. Basic C and Objective-C will not be covered here since there are a number of very good introductory texts available online and at the bookstore. This chapter covers aspects of C and Objective-C that are not ordinarily covered in introductory texts or are recent additions to the language.