iOS Programming: The Big Nerd Ranch Guide

Using Instances

In order to use an instance of a class (an object), you must have a variable that points to the object. A pointer variable stores the location of an object in memory, not the object itself. (It “points to” the object.) A variable that points to an object is declared like so:

P​a​r​t​y​ ​*​p​a​r​t​y​I​n​s​t​a​n​c​e​;​

This variable is named partyInstance. It is meant to be a pointer to an instance of the class Party. However, this does not create a Party instance – only a variable that can point to a Party object.

Creating objects

An object has a life span: it is created, sent messages, and then destroyed when it is no longer needed.

To create an object, you send an alloc message to a class. In response, the class creates an ...