NeXTSTEP Interface Builder (NIB) file parser prints a list of all connections defined in a NIB file. 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 file.