objective c - Avoiding, finding and removing memory leaks in Cocoa

Question

Memory (and resource) leaks happen. How do you make sure they don't?

What tips & techniques would you suggest to help avoid creating memory leaks in first place?

Once you have an application that is leaking how do you track down the source of leaks?

(Oh and please avoid the "just use GC" answer. Until the iPhone supports GC this isn't a valid answer, and even then - it is possible to leak resources and memory on GC)

Answer 1

In XCode 4.5, use the built in Static Analyzer.

In versions of XCode prior to 3.3, you might have to download the static analyzer. These links show you how:

Use the LLVM/Clang Static Analyzer

To avoid creating memory leaks in the first place, use the Clang Static Analyzer to -- unsurprisingly -- analyse your C and Objective-C code (no C++ yet) on Mac OS X 10.5. It's trivial to install and use:

1. Download the latest version from this page.
2. From the command-line, cd to your project directory.
3. Execute scan-build -k -V xcodebuild.

(There are some additional constraints etc., in particular you should analyze a project in its "Debug" configuration -- see http://clang.llvm.org/StaticAnalysisUsage.html for details -- the but that's more-or-less what it boils down to.)

The analyser then produces a set of web pages for you that shows likely memory management and other basic problems that the compiler is unable to detect.

If your project does not target Mac OS X desktop, there are a couple of other details:

1. Set the Base SDK for All Configurations to an SDK that uses the Mac OS X desktop frameworks...
2. Set the Command Line Build to use the Debug configuration.

(This is largely the same answer as to this question.)