If you would like to add to this page, please keep the terms in case-insensitive alphabetical order.

CF

Acronym for Core Foundation, which provides the fundamental data types and essential services for both the Cocoa and Carbon environments on Mac OS X. Core Foundation defines a set of C-based programming interfaces derived conceptually from the Foundation framework in Cocoa.

HUD

Acronym for "Heads up display." HUD panels are the black, semi-transparent panels used in "pro" applications like Aperture and third party applications like Pixelmator.

IB

Abbreviation for "Interface Builder."

id

An id is basically any Objective-C object. Since Objective-C is a dynamically typed language (meaning that the type of the object is determined when the program is run and is not "hard compiled" in), declaring objects as type "id" can be advantageous when dealing with potentially ambiguous objects. Below is an example of an id parameter in an NSTableView delegate method:

-(void)tableView:(NSTableView *)aTableView
  setObjectValue:(id)anObject
  forTableColumn:(NSTableColumn *)aTableColumn
             row:(int)rowIndex
{
  NSLog(@"Replacing '%@' with '%@'", [aTableView objectAtIndex:rowIndex], anObject);
  [aTableView replaceObjectAtIndex:rowIndex withObject:anObject];
}

ivar

Short for "instance variable" and pronounced "eye-var". Ivars refer to an instantiated object, i.e. memory representing an instance of a class. In the following code snippet, "myIvar" is the instance variable:
NSString *myIvar = [[NSString alloc] init];

NS

Short for "NeXTSTEP". This is most commonly seen prefixing the class names of the Foundation and AppKit frameworks. It is a holdover from the days when Cocoa was being developed by the NeXT corporation under the name NeXTSTEP. (Random trivia: the former prefix was actually NX—Apple transitioned to NS when it bought NeXT and revamped the OS.)