IOS_Memory_leak_detection

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1、Finding&FixingMemoryLeaksiniOSApps©2010StreamingColourStudiosMe:OwenGoss5yearsinconsolegamesindustryStreamingColourStudios-Summer2008iPhoneGames:Dapple(Feb2009)MonkeysinSpace(Nov2009)LandFormer(Jun2010)ChapteroniPhoneDebuggingHowmanyofyou...Howmanyofyou...AlreadyhaveanappintheApp

2、Store?Howmanyofyou...AlreadyhaveanappintheAppStore?Areworkingonyourfirstapp?Howmanyofyou...AlreadyhaveanappintheAppStore?Areworkingonyourfirstapp?AreaMacOSXdeveloper?Howmanyofyou...AlreadyhaveanappintheAppStore?Areworkingonyourfirstapp?AreaMacOSXdeveloper?HavenevertouchedObjective-C

3、before?Don’tworry...www.streamingcolour.com/blogThispresentationandtheexamplecodeIpresentwillallbemadeavailableaftertheconferenceonmyblog.ThePlan,ManWhat’saMemoryLeakRetain,Release&StuffCommonLeaksFinding&FixingLeaks-Tostart,I’lltalkspecificallyaboutwhataleakis-I’llgiveanoverviewo

4、fmemorymanagementiniOS-I’llgothroughsomecommonwaystointroduceleaks-We’lljumpintoXcodewithsomesamplecodeandactuallyfindandfixabunchofleaks.WhatisaMemoryLeak?Inordertotalkabouthowmemoryleaksoccur,howtofixthem,andwhythey’rebad,wefirstneedtodefinewhattheyare.Amemoryleakisapieceofallocated

5、memorythatnothingpointsto.Therearetwoimportantthingshere:1)we’retalkingaboutheapmemory,ormemorythat’sallocated.Think:pointers.2)We’retalkingaboutachunkofmemorythat’s“lost”ontheheap.Nothingreferencesitanymore.What’saLeak?Heap(memory)//a=0x0032ba80MyClass*a=[[MyClassalloc]init];//O

6、RinC++//MyClass*a=newMyClass();//ORinC//MyStruct*a=(MyStruct*)malloc(sizeof(MyStruct));Thepreviousslidestatedthataleakinvolvesapieceofallocatedmemory.ThisishowweallocatememoryinObj-C(andexamplesinC++andC).Thistakesachunkofheapmemoryofthesizeofourobjectandsays“Thismemoryisreserved

7、”.Thepointer,a,isjustanumberthatstorestheaddressoftheobjectinmemorysowecanfindit.What’saLeak?0x0...//Memoryleak!a=nil;Butifyouchangethevalueofthepointer,topointtosay,nil,thenthechunkofmemoryweallocatedcannolongerbefound.However,noonetoldtheOSthatitcouldbefreed,soit’sstilltherewith

8、nowaytobecleanedup.Thisisaleak.Thegoodne