Memory leaks NSMutableArray

[isoft]

Hi,

Im not sure it's me (Properly is..) but I just don't understand the memory leaks I get in my program after upgrading to 4.1

In my .h file I have:
NSMutableArray pieces;

In the Init method I do following:
pieces = [[NSMutableArray alloc] init];

Then I load some pieces to the array..

-(void) loadImages() {

for (int i = 0; i < piecesCount; i++) {

//Piece extends UIImageView, just added some new properties to this object
Piece *pieceImageView = [[Piece alloc] initWithImage:Image];
...
...

[pieces pieceImageView];

// Add puzzel piece to the view
[self.view insertSubviewieceImageView atIndex:subViewIndex];
subViewIndex++;

// Clean up
[pieceImageView release];
}


When the user have looked though the pieces and want to go to next view I (Same view new images)
I would like to clean up, then I call same method again (loadImages)


BUT, when I try to clean-up it looks like I get some leaks, and do not understand why.. I have many many different ways non of them works:

- (void) cleanUp() {

1)
NSMutableArray *delete = [NSMutableArray array];

for(Piece *p in pieces) {
[delete addObject];
[p removeFromSuperView];
}

for (Peice *dt in delete)
[pieces removeObject:dt];


2)
for (UIView *view in self.view.subviews) {

if ([view isKindOfClass:[Tile class]])
[view removeFromSuperview];

[pieces removeAllObjects];

3)
for(Piece *p in pieces)
[p removeFromSuperView];

// This crach, when removing from superview I can see I loose ref to it.. So why do I get the leak
[pieces release];
}

I hope one of you can tell me what Im doing wrong, I know it's me, just can't figure it out..

Thank you!

[smasher]

What type of object are you leaking, and from which line? Tiles or an array or both?

I'd write the cleanup like this:

for(Piece *p in pieces){
    [p removeFromSuperView];
}

[pieces removeAllObjects];

You don't want to release pieces (causing it to be destroyed) because you need it around when loadImages is called.

[isoft]

Originally Posted by smasher

What type of object are you leaking, and from which line? Tiles or an array or both?

I'd write the cleanup like this:

for(Piece *p in pieces){
    [p removeFromSuperView];
}

[pieces removeAllObjects];

You don't want to release pieces (causing it to be destroyed) because you need it around when loadImages is called.

The type of leak I get when I use Instruments it's the Piece obejcts (It match the amount in my array)

Each time when Im clearing the pieces I get the image leak!

If I use your sample above the for loop works just fine, but calling the [pieces removeAllObjects] crash the program!

I get this error: Program received signal: “EXC_BAD_ACCESS”.

Do not understand this error, this should be very simple but I must be missing something!

Thx for your reply!

[smasher]

EXC_BAD_ACCESS is common when you release too much.

Can you post your whole loadimages and cleanup method? Use [code] [ /code] tags to preserve the indentation.

Do you add more objects to "pieces" in any other method?

[isoft]

Im only adding images to my array in loadImages

-(void) loadImages {
    for (int i = 0; i < imagesToLoad; i++) {

        Piece *pieceImageView = [[Piece alloc] initWithImage:tileImage];

         // Here some calculation regarding the frame!
        pieceImageView.frame = pieceFrame;
        pieceImageView.originalPosition = orgPosition;
        pieceImageView.currentPosition = orgPosition;
			
        // free up some resources 
        pieceImage release];
			
        [pieces addObject:pieceImageView];
			
        // Add puzzel piece to the view
        [self.view insertSubview:pieceImageView atIndex:subViewIndex];
        subViewIndex++;

        // Clean up
        [pieceImageView release];
    }
}

if there is a double touch I get the find the piece tabbed

-(Piece *) getPieceAtPoint:(CGPoint) point {
	
	CGRect touchRect = CGRectMake(point.x, point.y, 1.0, 1.0);
	
	for( Piece *p in pieces ) {
		
		if( CGRectIntersectsRect(p.frame, touchRect) ) {
			return p; 
		}		
	}
	return nil;
}

I do not retain or relase this object anywhere!

When im done, and want to release my array and reload the view with new images I tried with the code you gave me!

for (Piece *p in pieces) 
    [p removeFromSuperview];

[pieces removeAllObjects]; // This line crash (EXC_BAD_ACCESS)

Before executing the line removeAllObjects I check the content of the array, there is 4 objects in the array as expected but they are all out of scope, which I think is because of the removeFromSuperview

[smasher]

What is this?

        // free up some resources 
        pieceImage release];

Is pieceImage involved with pieceImageView in any way?

[isoft]

Ohh sorry, type mistake.. Im working on two version right now, and have started renaming, so I wrote wrong:

pieceImage is the image which is loaded with UIImageView

It should have been:

-(void) loadImages {
    for (int i = 0; i < imagesToLoad; i++) {

        Piece *pieceImageView = [[Piece alloc] initWithImage:pieceImage];

         // Here some calculation regarding the frame!
        pieceImageView.frame = pieceFrame;
        pieceImageView.originalPosition = orgPosition;
        pieceImageView.currentPosition = orgPosition;
			
        // free up some resources 
        pieceImage release];
			
        [pieces addObject:pieceImageView];
			
        // Add puzzel piece to the view
        [self.view insertSubview:pieceImageView atIndex:subViewIndex];
        subViewIndex++;

        // Clean up
        [pieceImageView release];
    }
}

[smasher]

You're releasing pieceImage every time you create an ImageView; I'm surprised it doesn't crash right there. Don't release pieceImage inside the loop. You should only release it if you alloc'd it or retained it yourself, and only once.

That's probably why it doesn't crash when you leak the UIImageViews, but does crash when you dispose of them properly.

[isoft]

I do alloc the pieceImage in the for loop..

Sorry I didn't post that, but thought it did not have any meaning..

-(void) loadImages {
    for (int i = 0; i < imagesToLoad; i++) {

	CGImageRef pieceImageRef = CGImageCreateWithImageInRect(
                                                  orgImage.CGImage, frame );
	
        UIImage *pieceImage = [UIImage imageWithCGImage:pieceImageRef];
        [Piece *pieceImageView = [[Piece alloc] initWithImage:pieceImage];

         // Here some calculation regarding the frame!
        pieceImageView.frame = pieceFrame;
        pieceImageView.originalPosition = orgPosition;
        pieceImageView.currentPosition = orgPosition;
			
        // free up some resources 
        pieceImage release];
        CGImageRelease(pieceImageRef);
			
        [pieces addObject:pieceImageView];
			
        // Add puzzel piece to the view
        [self.view insertSubview:pieceImageView atIndex:subViewIndex];
        subViewIndex++;

        // Clean up
        [pieceImageView release];
    }
}

[smasher]

You did not alloc pieceImage in the loop; you created it using imageWithCGImage:, not with alloc/init.

I still think you are over-releasing pieceImage. The cleanup code looks correct to me.

[Bertrand21]

Originally Posted by smasher

You did not alloc pieceImage in the loop; you created it using imageWithCGImage:, not with alloc/init.

I still think you are over-releasing pieceImage. The cleanup code looks correct to me.

Yes exactly. Your releasing an autorelease object.

[isoft]

Thx a lot for your help...

Feel a bit stupid now, what you mentioned did the trick!

Have a good one!

[smasher]

No worries, sometimes the cause is far from the effect.

When getting an EXC_BAD_ACCESS you can also turn on NSZombieEnabled; that would have told you that you're accessing a UIImage that has been deallocated, which would have been another clue to the real issue.