MemoryManagement

Memory Management Overview Page

MemoryManagement is a very central topic to programming. Many different systems for MemoryManagement have been devised, but since this is a Cocoa site, we can ignore most of them.

In Cocoa with Objective-C, MemoryManagement is handled by RetainingAndReleasing objects. Starting with Objective-C 2.0 and Mac OS X 10.5, and also when you are programming Cocoa with Java, you have the added option of using GarbageCollection.

The best thing you can do to learn memory management is to read the first two lines of RulesOfThumb. Then read them again.

CocoaDev articles dealing with MemoryManagement:

• Basics
  • AutoRelease
  • MemoryLeaks
  • RetainingAndReleasing - Basics of MemoryManagement
  • RulesOfThumb - in case you missed this in the introductory remarks

• Details
  • AutoReleasePool - How autorelease works
  • HowToFindMemoryLeaks - mainly discussing the use of the leaks program
  • ObjectCreation - Responsibility for releasing objects
  • RetainCount
  • RetainCycles - Something to avoid
  • RetainReleaseTips - Sample code for basic RetainingAndReleasing
  • RetainingImmutableVars - Should I retain or copy an object?

• Further
  • AccessorMethods - Sample Code for memory-safe accessor methods
  • DebuggingAutorelease - Hunting down over-released objects
  • DefensiveCopies - short intro to the concept of "defensive copies"
  • HowToUsePointers - Insofar as ObjC is a superset of C, you also have old friends malloc, calloc, and free
  • NSZone - Advanced topic for optimization
  • WeakReferences - A concept to avoid RetainCycles in massively multithreaded apps

External articles dealing with MemoryManagement

• http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/index.html - "Memory Management Programming Guide for Cocoa"
• http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaFundamentals/CocoaObjects/chapter_3_section_5.html - "The Life Cycle of a Cocoa Object"
• http://www.stepwise.com/Articles/Technical/HoldMe.html - "Hold Me, Use Me, Free Me." By: Don Yacktman.
• http://www.stepwise.com/Articles/Technical/2001-03-11.01.html - "Very simple rules for memory management in Cocoa" By mmalcolm crawford
• http://www.stepwise.com/Articles/Technical/2002-06-11.01.html - "Accessor Methods Revisited" By mmalcolm crawford
• http://www.macdevcenter.com/pub/a/mac/2003/06/10/memory_mgmt.html - an article on the subject by RobRix.
• http://www.mulle-kybernetik.com/artikel/Optimization/opti-2.html - Allocation Basics & Foundation - an article in the series on optimizing Objective-C.
• http://www.mac-developer-network.com/shows/podcasts/lnc/lnc010/ - Podcast on what memory is and memory management in Cocoa with Steve Scott and Uli Kusterer.
• http://www.masters-of-the-void.com/book5.htm - A chapter from a C tutorial aimed at Mac programmers that explains what memory is.
• http://mattpatenaude.com/ch3-memory-management.html - "Memory Management in Cocoa", from an upcoming eBook by the {13bold} duo

Non OS X, but some good background information on memory management principles:

• Learning the basics of buffer overflows [http://www-106.ibm.com/developerworks/security/library/s-overflows/]
• Self-manage data buffer memory [http://www-106.ibm.com/developerworks/library/wa-memmng/?ca=dgr-lnxw07Self-manageMemory]