Professional Xcode® 3

Chapter 19. Performance Analysis

WHAT'S IN THIS CHAPTER?

• Performance analysis best practices

• Analyzing code-level performance with Shark

• Analyzing everything else with Instruments

• Solving common performance problems

Whether it's a rollercoaster ride or a visit to the dentist, a lot of times you just want things to go faster — and the applications you build with Xcode are no exception. Speeding up an application entails finding and eliminating inefficient code, making better use of the computer's resources, or just thinking differently. Neither Xcode nor I can help you with the last one. Sometimes the most dramatic improvements in a program are those that come from completely rethinking the problem. There are, sadly, no developer tools to simulate your creativity.

The more mundane approaches are to reduce the amount of waste in your application and to harness more of the computer system's power. To do that you first need to know where your application is spending its time and learn what resources it's using. In simple terms, to make your application run faster you first need to know what's slowing it down. This is a process known as performance analysis, and for that, Xcode offers a number of very powerful tools.

Recent versions of Xcode consolidate a wide variety of performance analysis tools that, in prior versions, were individual applications. In Xcode 3.2, the former rag-tag band of developer gizmos has been gathered together under a single umbrella called Instruments. I do not exaggerate ...