Instruments - iOS Programming: The Big Nerd Ranch Guide - page 589

This table shows every memory allocation in the application. There are a lot of objects
here, but let's look at the objects that your code is responsible for creating. First, draw
some lines in TouchTracker . Then, type Line in the Instrument Detail search box in the
top right corner of the window.
This will filter the list of objects in the Object Summary table so that it only shows in-
stances of Line ( Figure 21.7 ).
Figure 21.7 Allocated Lines
The # Living column shows you how many line objects are currently allocated. Live
Bytes shows how much memory these living instances take up. The # Overall column
shows you how many lines have been created during the course of the application - even
if they have since been deallocated.