Objective-C defines the type
id, which is known as the Anonymous Type. The
id type tells the compiler that a variable points to an object but doesn’t give the compiler any more specific information about the kind of object, hence the object is anonymous. Objective-C programmers quickly become familiar with the pervasive use of the Anonymous Type and forget that this feature is seldom encountered in other languages. Objective-C’s Anonymous Type and Cocoa’s Heterogeneous Containers deserve special recognition as patterns in their own right and facilitators for other patterns.
Use the Anonymous Type pattern to send messages to anonymous objects, including objects that are not available ...