Learning Cocoa

Create Graphical User Interfaces in Cocoa

In this section you’ll see how Cocoa and Interface Builder combine to simplify and accelerate the process of constructing applications with a graphical user interface. You’ll learn about:

• Windows. A window is an area on the screen (usually, but not always, rectangular) in which an application displays things such as controls, fields, text, and graphics.

• Nib files. Nib files are files created by Interface Builder that contain windows as well as other user interface objects.

• Outlets. Outlets are special instance variables created by Interface Builder that allow objects to send messages to one another.

Finally, you’ll apply what you’ve learned by creating a Cocoa application that displays a window with a single text field containing the current date and time.

Windows in Cocoa

A window in Cocoa looks very similar to windows in other user environments such as Microsoft Windows or Mac OS 9. A window can be moved around the screen, and windows can be stacked on top of one another like pieces of paper. A typical Cocoa window has a titlebar, a content area, and several control objects.

NSWindow and the window server

Many user interface objects other than the standard window are windows. Menus, pop-up menus, and scrolling lists are primarily windows, as are dialog boxes, alerts, Info windows, and tool palettes, to name a few. In fact, anything drawn on the screen must appear in a window. End users, however, may not recognize or refer to them as ...