Releasing NSMutableArray in dealloc causes the app to crash - ios

Question

I have a UIView which holds a UITableView. This table is being populated by an NSMutableArray.
I initialized both the array and the table in the UIView's initWithFrame: method.
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self)
{
bookTable = [[UITableView alloc]initWithFrame:CGRectMake(100, 108, 260, 535)];
bookArray = [[NSMutableArray alloc]init]; //this array will be populated later
//other codes
}
return self;
}
I release them in dealloc:
- (void)dealloc
{
[bookTable release];
[bookArray release];
[super dealloc];
}
The problem is when the app crashes in dealloc. It produces the error: [CALayer release]: message sent to deallocated instance 0x82db660
I looked everywhere in my code and I'm sure that I didn't overreleased anything. I decided to remove the [bookArray release] in dealloc, and it stopped crashing. I ran the Analyze and it doesn't give me any potential leaks.
Can anyone explain to me why releasing the array in dealloc causes the crash?
NOTE:
Both the table and the array are instance variables of the view.
EDIT:
Code for populating the array:
NSString *sql = [NSString stringWithFormat:#"SELECT BookName FROM books WHERE UserID=%d", userId];
booksArray = [sqlite executeQuery:sql];
Please note that I am using a sql wrapper.

Answer 1

Here lies the problem
booksArray = [sqlite executeQuery:sql];
The array returned by the sqlite is an autoreleased object. You must either retain it or remove release from `dealloc'.
booksArray = [[sqlite executeQuery:sql] retain];
Since it is autoreleased object, releasing it in dealloc results in crash when system also tries to release it.
And do remove the array initialization in init method, it's redundant.

Answer 2

Problem is here only, I assume.
booksArray = [sqlite executeQuery:sql];
the executeQuery method might be returning an autoreleased NSMutableArray or something like this might be written inside executeQuery
NSMutableArray* tempArray = [NSMutableArray arrayWithCapacity:0];
If its like this, it should already be in autoreleased mode, hence no release in dealloc method.
UPDATE
Also, as0sign property to the array.
#property (nonatomic, retain) NSMutableArray* booksArray;
And then, wherever you use it, use it as self.booksArray
self.booksArray = [sqlite executeQuery:sql];
This way, it would be proper memory management and then release the array in dealloc.

Answer 3

Change the return statement of your executeQuery method like [array autorelease]
Replace booksArray = [sqlite executeQuery:sql]; by booksArray = [[sqlite executeQuery:sql] retain];
If you wrote property for the booksArray like #property(nonatomic, retain) NSMutableArray *bookArray; then you can replace step 2 by self.bookArray = [sqlite executeQuery:sql];
Your issue is you are returning an released object from the executeQuery method (You mentioned it on your comment). That's why you are getting the error

Answer 4

I would suggest to create a property for the booksArray like this:
#property (nonatomic, retain) NSMutableArray *bookArray;
An when you populate it try this code:
self.bookArray = [NSMutableArray arrayWithArray:[sqlite executeQuery:sql]];
That'll create an autoreleased copy of the returned array which is then "auto"-retained by the property.
Of course you should make sure, that the array return by [sqlite executeQuery:sql] is autoreleased.