iOS：滚动UITableView时，应用程序崩溃/内存已满

Question

One of the views od my app shows a list of images. When I scroll that list several times then my app crashes. I profiled it with instrument and it seems that the cells of the list are taking more memory as the list is scrolled.

Should a custom UITableCell be 'autoreleased' when returned from tableView:cellForRowAtIndexPath: ? (if I do, I have a crash on iOS 4.3 / it's fine in iOS 5.0 and 6.1)

This custom UITableCell have several pictures drawn into its 'contentView'. Those pictures are actually custom UIButton in which I set the background image.

The images are managed with HJManagedImageV

code for custom UIButton :

@implementation ProductTileButtonIpad

@synthesize product;

- (id)initWithFrame:(CGRect)frame andProduct:(Product *)aProduct {

    if (self = [super initWithFrame:frame]) {

        self.product = aProduct;

        self.productTileView = [[[HJManagedImageV alloc] initWithFrame:self.frame] autorelease];
        self.productTileView.callbackOnSetImage = self;
        self.productTileView.url = some picture url

        [[ImageManager instance] manage:self.productTileView];
    }

    return self;
}


#pragma mark -
#pragma mark HJManagedImageV delegate

-(void) managedImageSet:(HJManagedImageV*)mi {

    [self setBackgroundImage:mi.image forState:UIControlStateNormal];
}

-(void) managedImageCancelled:(HJManagedImageV*)mi {
}


- (void)dealloc {

    NSLog(@"deallocating ProductTileButtonIpad");

    [self.product release];
    [self.productTileView release];

    [super dealloc];
}

@end

code for the custom cell

@implementation ProductGridCellIpad

@synthesize products, parentController;

- (void)initializeWithProducts:(NSMutableArray *)productsToShow{

    self.products = productsToShow;

    // clear possible old subviews
    for (UIView *v in self.contentView.subviews) {
        [v removeFromSuperview];
    }

    NSInteger width = 240;
    NSInteger height = 240;

    Product *product0 = [products objectAtIndex:0];

    self.productTile0 = [[[ProductTileButtonIpad alloc] initWithFrame:CGRectMake(12, 12, width, height) andProduct:product0] autorelease];

    [self.productTile0 addTarget:self.parentController action:@selector(selectedProduct:) forControlEvents:UIControlEventTouchUpInside];

    [self.contentView addSubview:self.productTile0];

    [self.productTile0 release];

    if ([self.products count] > 1) {

        Product *product1 = [products objectAtIndex:1];

        self.productTile1 = [[[ProductTileButtonIpad alloc] initWithFrame:CGRectMake(12 + width + 12, 12, width, height) andProduct:product1] autorelease];

        [self.productTile1 addTarget:self.parentController action:@selector(selectedProduct:) forControlEvents:UIControlEventTouchUpInside];

        [self.contentView addSubview:self.productTile1];

        [self.productTile1 release];
    }

    if ([self.products count] > 2) {

        Product *product2 = [products objectAtIndex:2];

        self.productTile2 = [[[ProductTileButtonIpad alloc] initWithFrame:CGRectMake(2*(12 + width) + 12, 12, width, height) andProduct:product2] autorelease];

        [self.productTile2 addTarget:self.parentController action:@selector(selectedProduct:) forControlEvents:UIControlEventTouchUpInside];

        [self.contentView addSubview:self.productTile2];

        [self.productTile2 release];
    }
}

- (void)dealloc {

    NSLog(@"deallocating ProductGridCellIpad");

    if(self.products)
        [self.products release];

    if(self.productTile0)
        [self.productTile0 release];

    if(self.productTile1)
        [self.productTile1 release];

    if(self.productTile2)
        [self.productTile2 release];

    [super dealloc];
}

@end

and here's the code that creates the cell :

    NSString *productGridCellIpadIdentifier = @"ProductGridCellIpadIdentifier";

    ProductGridCellIpad *cell = [tableView dequeueReusableCellWithIdentifier:productGridCellIpadIdentifier];

    if(cell == nil) {

        cell = [[ProductGridCellIpad alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:productGridCellIpadIdentifier];

        [cell setFrame:CGRectMake(0, 0, self.view.frame.size.width, 244)];
    }

    [cell setParentController:self];
    [cell initializeWithProducts:products];

    return cell;

As it is now the code crashes right away on iOS 4.3. It works on iOS 5 and 6 but the app still crashes after a certain time of use/scrolling the table.

I don't use ARC.

I added some NSLog in the dealloc methods to see what's happening and I can see lots of "deallocating ProductTileButtonIpad" but I never see "deallocating ProductGridCellIpad"

My app easily reaches memory usage of 400Mb.

What am I doing wrong here?

If some of you have any thoughts, ideas that could help my understanding it would be much appreciated :)

Answer 1

Cells are reused, so you shouldn't see "dealloc ProductGridCellIpad" when scrolling. Instead verify whether recycling really is working or whether you keep creating new cells all the time:

ProductGridCellIpad *cell = [tableView dequeueReusableCellWithIdentifier:productGridCellIpadIdentifier];

if(cell == nil) {
    cell = [[ProductGridCellIpad alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:productGridCellIpadIdentifier];
    [cell setFrame:CGRectMake(0, 0, self.view.frame.size.width, 244)];
    NSLog("Cell created");
}
else {
    NSLog("Cell recycled");
}

If that's ok, I'd check releasing. For example you have "self.productTile2" both autorelease and release, which might confuse memory management.

Also I'd check carefully the "parentController", which might prevent things from being released. You need to set it to nil.

Answer 2

是的，当使用alloc] init..时，您显然必须autorelease单元格dequeueReusableCellWithIdentifier返回自动autorelease的单元格。