XIB is the file format for Interface Builder, which is a development tool for the Mac OS X & iOS platforms.
interface-builder is a software development application for Apple's Mac os-x operating system. It is part of xcode (formerly Project Builder), the Apple Developer Connection developer's toolset. Interface Builder allows cocoa and Carbon developers to create interfaces for applications using a graphical user interface. The resulting interface is stored as a .nib file, short for NeXT Interface Builder, or more recently, as a .xib (xib) file.
Interface Builder is descended from the NeXTSTEP development software of the same name. A version of Interface Builder is also used in the development of OpenStep software, and a very similar tool called Gorm exists for GNUstep. On March 27, 2008, a specialized iPhone version of Interface Builder allowing interface construction for iPhone applications was released with the iPhone SDK Beta 2. As of Xcode 4, Interface Builder no longer exists as a separate application, and its functionality is directly integrated into Xcode.
The Interface Builder editor within Xcode makes it simple to design a full user interface without writing any code. Simply drag and drop windows, buttons, text fields, and other objects onto the design canvas to create a functioning Mac, iPhone, or iPad user interface.
Because Cocoa and Cocoa Touch are built using the Model-View-Controller pattern, it is easy to independently design your interfaces, separate from their implementations. User interfaces are actually archived Cocoa or Cocoa Touch objects (saved as .nib files), and OS X and iOS will dynamically create the connection between UI and code when the app is run.
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