Testing Code with Instruments - Xcode 4 - page 425

Simultaneous parallel testing: You can track and monitor multiple instruments in the same application;
on OS X, you can monitor multiple applications simultaneously.
Test recording: Instruments creates a record of each run on separate tracks. You can save the record and
reload it to compare it with other runs.
Customized instruments: Advanced developers can create their own instruments.
Beginning with Instruments
Instruments runs in an independent window, as shown in Figure 16.1. You can launch it intwo ways:
Select Product⇒Profile in the main Xcode menu to build a project and load it into Instruments. By de-
fault, Instruments is automatically attached to (set up to profile) the current project. The monitored applica-
tion is called the target.
Launch Instruments independently from Finder or the Dock. Instruments is in the main Xcode
/Developer/Applications directory. When you launch Instruments manually, you must attach it to
a target yourself. Usually, the target is your project, but you can monitor any running process, with some
limitations, described later in this chapter.
FIGURE 16.1
A first view of Instruments, showing one instrument out of the many that are available
Understanding Instruments
Instruments is a multi-track recorder for system events and statistics, similar to a music or video recorder.