Xcode

Apple’s developer tools package. It includes the Xcode application, Interface Builder (Apple’s graphical interface for constructing GUIs), a collection of other tools and APIs, and the Cocoa and Carbon APIs
The Xcode application works equally well with the Cocoa object-oriented framework and the Carbon procedural API for Mac OS X. It provides interfaces to several other tools and compilers, and can display documentation for any symbol in any of the Mac OS X APIs and any command-line tool installed on your system. Its code-completion feature brings up a list of all the symbols (type names, variables, class names, and so on) that are permitted at a chosen point in the code as you write it.