ios - Sending release after [[NSString alloc] init] causes EXIT_BAD_ACCESS -

i think there did not understand in memory management in xcode , when or not release objects avoid memory leaks. have been reading presentation, since there no audio dont understand sides: http://www.slideshare.net/owengoss/finding-and-fixing-memory-leaks-in-ios-apps-5251292

here simple code of app issue:

// implement viewdidload additional setup after loading view, typically nib. - (void)viewdidload {     [super viewdidload];   nsstring *mybundlename = [[nsstring alloc] init];  nsstring *mybundleversion = [[nsstring alloc] init];  nsstring *mybundlebuild = [[nsstring alloc] init];  nsstring *myiosname = [[nsstring alloc] init];  nsstring *myiosversion = [[nsstring alloc] init];   mybundlename = [[nsbundle mainbundle] objectforinfodictionarykey:@"cfbundlename"];  mybundleversion = [[nsbundle mainbundle] objectforinfodictionarykey:@"cfbundleshortversionstring"];  mybundlebuild = [[nsbundle mainbundle] objectforinfodictionarykey:@"cfbundleversion"];  myiosname = [[uidevice currentdevice] systemname ];  myiosversion = [[uidevice currentdevice] systemversion];   self.versionbuildlabel.text = [nsstring stringwithformat:@"%@ version %@ build %@ on %@ %@", mybundlename, mybundleversion, mybundlebuild, myiosname, myiosversion];   [mybundlename release];  [mybundleversion release];  [mybundlebuild release];  [myiosname release];  [myiosversion release];  } 

if try run

 [mybundlename release];  [mybundleversion release];  [mybundlebuild release];  [myiosname release];  [myiosversion release]; 

then application crashes with

[session started @ 2010-12-02 14:08:47 +0700.] gnu gdb 6.3.50-20050815 (apple version gdb-1472) (wed jul 21 10:53:12 utc 2010) copyright 2004 free software foundation, inc. gdb free software, covered gnu general public license, , welcome change and/or distribute copies of under conditions. type "show copying" see conditions. there absolutely no warranty gdb.  type "show warranty" details. gdb configured "x86_64-apple-darwin". sharedlibrary apply-load-rules attaching process 26707. pending breakpoint 1 - ""homevc.m":49" resolved (gdb) continue current language:  auto; objective-c [switching process 26707] [switching process 26707] program received signal:  “exc_bad_access”. (gdb)  

i thought doing right thing releasing intermediate variables used make code easier understand.

what problem here?

nb: face similar problems in other portion of code, simplest example causes me problems, there notion did not understand.

when assign variables items [uidevice currentdevice] , [nsbundle mainbundle], objects come autoreleased. since they're autoreleased, ios automatically handles memory management of objects you. that's why app crashes when try manually release them.

don't initialize nsstrings new objects (i.e. [[nsstring alloc] init]). initialize them convenience methods right away:

nsstring *mybundlename = [[nsbundle mainbundle] objectforinfodictionarykey:@"cfbundlename"]; nsstring *mybundleversion = [[nsbundle mainbundle] objectforinfodictionarykey:@"cfbundleshortversionstring"]; nsstring *mybundlebuild = [[nsbundle mainbundle] objectforinfodictionarykey:@"cfbundleversion"]; nsstring *myiosname = [[uidevice currentdevice] systemname]; nsstring *myiosversion = [[uidevice currentdevice] systemversion]; 

and don't call release on of them. way method never has ownership of these objects; happen passed use.