302 CHAPTER 9: Performance ’n’ Stuff^
Record/Stop
The Record/Stop button will start and end a recording session. When depressed, it will
launch your app and start all of the pretty little squiggly tracks looking like a fancy-pants
EKG machine. Click it again, and it will terminate your session. You can now have the
option to save it or wipe it out by starting a new session. If all you want is to pause a
session so that you can examine some specific data, the Pause button will do the trick.
The Repeat UI Input button is used only for flexing desktop apps and not those on iOS
devices. See Figure 9-9.Figure 9-9. The Pause/Record/Repeat UI buttons and target selectorNote The Repeat UI button is particulary interesting because it is used to automate user
interaction. You can record a session and then have Instruments repeat it over and over for
stress testing or to find that elusive bug that only shows up every once–in-a-while.Instrument Inspector
Clicking the ‘‘i’’ button on the upper-right corner of the Analyzer’s window will launch its
inspector, as shown in Figure 9-10. It will let you set what specific items you want to
observe such as the number of lines rendered or redundant state changes. (Remember
the recommendation earlier about minimizing state changes? This will help you fix that.)