Retain property and EXC_BAD_ACCESS on NSArray - objective-c

Question

I have gone through all the relevant posts on EXC_BAD_ACCESS but failed to have the concept clear yet. Maybe I should first work on learning the basic concepts but right now I need to get on this issue.. So, stepped in to get some expert help..
Here is my code (I have pasted only the relevant part)
//In .h
//=====
#interface GUIMainController : GUIController {
::
::
NSArray* shufflePositionArray;
}
#property (retain)NSArray* shufflePositionArray;
//In .mm
//=======
#synthesize shufflePositionArray;
-(void)start
{
::
NSString* shufflePositionArrayPlistPath=nil;
NSString* shufflePositionArrayPlistPathFromConfiguration=
#"/MyApp/Configuration/ShufflePositionArray.plist";
if ([[NSFileMngrdfltMngr]fileExistsAtPath:shufflePositionArrayPlistPathFromConfig])
{
self.shufflePositionArray=
[NSArrayarrayWithContentsOfFile:shufflePositionArrayPlistPathFromConfig];
}
if (self.shufflePositionArray==nil) {
shufflePositionArrayPlistPath=
[thisBundle pathForResource:#"ShufflePositionArray" ofType:#"plist"];
if (shufflePositionArrayPlistPath!=nil) {
self.shufflePositionArray=
[NSArray arrayWithContentsOfFile:shufflePositionArrayPlistPath];
}
}
}
//From another method:
//====================
-(void)shuffleWindow
{
::
if (shufflePositionArray!=nil && [self.shufflePositionArray count]!=0){
:: // some code
if (shufflePositionArray!=nil && [self.shufflePositionArray count]!=0){
::
:: // some code
processwindowlocation_=(processwindowlocation_+1)%[self.shufflePositionArray count];
// ######## there is a crash here !!!!!! #############
}
}
}
//And then..we release it here:
//==============================
-(void)dealloc {
if(shufflePositionArray!=nil){
[shufflePositionArray release];
}
[super dealloc];
}
I am completely new to obj-C, any sort of help would be appreciated.
Thanks in advance.
Here is the crash:
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000018
VM Regions Near 0x18:
-->
__TEXT 000000010d89a000-000000010d927000 [ 564K] r-x/rwx SM=COW /Ihome/MyAppCE.app/Contents/MacOS/MyAppCE
Application Specific Information:
objc_msgSend() selector name: count
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libobjc.A.dylib 0x00007fff82c5d62f objc_msgSend_vtable9 + 47
1 com.apple.AppKit 0x00007fff88842b05 +[NSScreen screens] + 847
2 com.apple.AppKit 0x00007fff88844575 +[NSScreen _zeroScreenHeight] + 44
3 com.apple.AppKit 0x00007fff888b15cf _NSShapeRoundedWindowWithWeighting + 61
4 com.apple.AppKit 0x00007fff888507c3 -[NSThemeFrame shapeWindow] + 336
5 com.apple.AppKit 0x00007fff888b055c -[NSThemeFrame setFrameSize:] + 457
6 com.apple.AppKit 0x00007fff888af68f -[NSWindow _setFrame:updateBorderViewSize:] + 929
7 com.apple.AppKit 0x00007fff888aee04 -[NSWindow _oldPlaceWindow:] + 1142
8 com.apple.AppKit 0x00007fff888ae2b9 -[NSWindow _setFrameCommon:display:stashSize:] + 1837
9 com.Apple.Phoenix.UI 0x0000000110580045 -[GUIMainController shuffleWindow] + 1477 (GUIMainController.mm:470)
10 com.Apple.Phoenix.UI 0x0000000110586aef -[GUIPeriodicController periodic:] + 2399 (GUIPeriodicController.mm:219)
11 com.apple.Foundation 0x00007fff86867463 __NSFireTimer + 96
12 com.apple.CoreFoundation 0x00007fff81df5804 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
13 com.apple.CoreFoundation 0x00007fff81df531d __CFRunLoopDoTimer + 557
14 com.apple.CoreFoundation 0x00007fff81ddaad9 __CFRunLoopRun + 1529
15 com.apple.CoreFoundation 0x00007fff81dda0e2 CFRunLoopRunSpecific + 290
16 com.apple.HIToolbox 0x00007fff83dc6eb4 RunCurrentEventLoopInMode + 209
17 com.apple.HIToolbox 0x00007fff83dc6b94 ReceiveNextEventCommon + 166
18 com.apple.HIToolbox 0x00007fff83dc6ae3 BlockUntilNextEventMatchingListInMode + 62
19 com.apple.AppKit 0x00007fff8887f533 _DPSNextEvent + 685
20 com.apple.AppKit 0x00007fff8887edf2 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 128
21 com.Apple.Phoenix.UI 0x0000000110594b52 processUIEvent() + 290 (PhoenixCECocoaGUI.mm:363)
22 com.Apple.Phoenix.UI 0x000000011058e152 Phoenix::Core::UICocoaImpl::processEvent() + 44 (UICocoaImpl.mm:61)
23 com.Apple.MyAppCE 0x000000010d8ae62e main + 2302 (mainer.cpp:180)
24 com.Apple.MyAppCE 0x000000010d89b604 start + 52
Thread 0 crashed with X86 Thread State (64-bit):
rax: 0x000000000000000f rbx: 0xffffffffffffffff rcx: 0x0000000001010101 rdx: 0x0000000000000001
rdi: 0xffffffffffffffff rsi: 0x00007fff7268ea80 rbp: 0x00007fff523631b0 rsp: 0x00007fff52363028
r8: 0x00007fff72435a30 r9: 0x00007fff72435a01 r10: 0x0000000000000000 r11: 0x00007f968c000600
r12: 0x0000000000000000 r13: 0x0000000000000000 r14: 0x0000000000000001 r15: 0x000000000000000c
rip: 0x00007fff82c5d62f rfl: 0x0000000000010206 cr2: 0x0000000000000018

Answer 1

If you have a crash, post the backtrace.
Assuming you haven't cut out some relevant code, the only way that processwindowlocation_=(processwindowlocation_+1)%[self.shufflePositionArray count]; could crash (assuming that that is actually the line of the crash) is if either self is invalid or the shufflePositionArray is invalid.
Note that invalid does not mean nil; nil would just return 0 for the count.
Note, also, that the check for non-nil here is pointless:
if(shufflePositionArray!=nil){
[shufflePositionArray release];
}
That crash is odd. I wouldn't really expect a crash there given your code.
Try turning on Zombie detection (Instruments -- Google can find more info, if you need) and seeing if it is an over-release issue.