Objective-C Fundamentals

278 CHAPTER 14 Debugging techniques
14.2 Understanding NSLog
In this book you’ve utilized the NSLog function extensively to emit diagnostic messages
to the Xcode debugger console window. What you may not realize is that NSLog continues
to log messages even when your application is used outside of the debugger. It
even logs messages once a user purchases your application from the iTunes App Store
and runs it on their own device. Where do these log messages end up, and how do you
retrieve them?
To answer these questions, deploy the DebugSample application onto your real
iPhone or iPad device, and run the application a couple of times (see appendix A for
details if you haven’t done this before). When you reconnect the device to your computer,
you can bring up the Xcode Organizer window (Shift-Cmd-2), which should
look similar to figure 14.2.
This window can be used for a wide range of tasks, such as uninstalling applications,
maintaining device provisioning profiles, and capturing application crash reports or
screenshots. In this case, you want to be in the Console section, as shown in figure 14.3.
Figure 14.2 The Xcode Organizer window showing a list of connected iOS devices. Using the various
tabs, you can control different aspects of your connected device, such as installing and uninstalling
applications, maintaining provisioning profiles, capturing screenshots, and reviewing application
crashes and log files.