memory management: am i doing something wrong here?

In a very small number of cases in my iphone app, I get a crash after the for loop in the code below:

ABAddressBookRef addressBookInit = ABAddressBookCreate();

CFMutableArrayRef abContacts =
(CFMutableArrayRef)ABAddressBookCopyArrayOfAllPeople(addressBookInit); // get array of all contacts
CFArraySortValues (abContacts, CFRangeMake(0, CFArrayGetCount(abContacts)), (CFComparatorFunction)ABPersonComparePeopleByName, (void *)ABPersonGetSortOrdering());

NSArray *copypeople = (NSArray *) abContacts;
NSMutableArray *tempTheadlist = [[NSMutableArray alloc] init];

for (int i=0; i < copy开发者_运维知识库people.count; i++)
{
   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
   ABRecordRef record = [copypeople objectAtIndex:i];
   if (blah blah)
         [tempThreadList addObject: someObject];
   [pool release];
}

// POINT OF CRASH AFTER LOOP ENDS

if (tempTheadlist.count > 0)
        [NSThread detachNewThreadSelector: @selector(loading_pictures:) toTarget:self withObject:tempTheadlist];


[tempTheadlist release];
[copypeople release];
CFRelease(addressBookInit);

Any reason why it should crash at any point here?

(1) ABAddressBookCopyArrayOfAllPeople() returns a CFArrayRef, not a CFMutableArrayRef.

(2) All the casts between CFArrayRef, CFMutableArrayRef, and NSArray are irrelevant. NSArray and CFArray are synonymous.

(3) The autorelease pool in the for() loop is irrelevant. There aren't any new objects being created in the for() loop and, thus, nothing to fall in the pool. Nor will objectAtIndex: retain/autorelease the objects.

(4) That you are sorting the array returned by ABAddressBookCopyArrayOfAllPeople() may likely be a crash trigger. That function is declared as returning a CFArrayRef() and it should be treated as immutable.

If the app is crashing, post the backtrace of the crash. Without that, it is hard to tell what is specifically triggering the crash. Is it crashing in the thread that ran the above code? ... or crashing in the newly created thread?