Information Technology Reference
In-Depth Information
You can see there's an immense amount of detail in the display. The Allocations instrument (refer to Figure
16.2) literally lists every object in memory. You can monitor the creation and destruction of specific class in-
stances and view stack traces for each creation event. You can also get more general statistics about created and
destroyed objects, the total memory footprint of the application, and so on. Not all instruments display this
much detail; others are simpler summaries of less complex application states.
CAUTION
Some features work at a low level, so you need a basic understanding of Cocoa and OS X/iOS internals to get the
most from certain instruments. You can use Instruments without this knowledge, but you will miss the more
powerful and productive features.
NOTE
Because some instruments literally modify the OS kernel as it's running, you may be asked for your OS X user-
name and password before they grant low-level access. The kernel changes are transparent and temporary.
Introducing the toolbar
The toolbar includes the most important controls and is visible unless you hide it using the button at the top
right. The features in the toolbar are described in the following sections.
