Question

I am using a scrollview to display various items in a horizontal fashion.

How can I “reuse the cells” to conserve memory:

Edit: Apologies for not being clear. I plan to place a few labels and and another ImageView inside each ImageView so I am keen to reuse this each time instead of instantiating new items each time. e.g. change the image’s and update the labels instead of re-create it.

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    [super viewDidLoad];

    // load all the images from our bundle and add them to the scroll view
//  NSUInteger i;
    for (int i = 0; i <= 150; i++)
    {
        NSString *imageName = @"tempImage.jpg";
        UIImage *image = [UIImage imageNamed:imageName];
        UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

        // setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
        CGRect rect = imageView.frame;
        rect.size.height = kScrollObjHeight;
        rect.size.width = kScrollObjWidth;
        imageView.frame = rect;
        imageView.tag = i;  // tag our images for later use when we place them in serial fashion
        [self.bestSellScrollView addSubview:imageView];
        [imageView release];
    }

    [self layoutScrollImages];  // now place the photos in serial layout within the scrollview
}

- (void)layoutScrollImages
{
    UIImageView *view = nil;
    NSArray *subviews = [self.bestSellScrollView subviews];

    // reposition all image subviews in a horizontal serial fashion
    CGFloat curXLoc = 0;
    for (view in subviews)
    {
        if ([view isKindOfClass:[UIImageView class]] && view.tag > 0)
        {
            CGRect frame = view.frame;
            frame.origin = CGPointMake(curXLoc, 0);
            view.frame = frame;

            curXLoc += (kScrollObjWidth);
        }
    }

    // set the content size so it can be scrollable
    [self.bestSellScrollView setContentSize:CGSizeMake((150 * kScrollObjWidth), 
                                                       [self.bestSellScrollView bounds].size.height)];
}

Answer 1

If you mean like what happens with respect UITableViewCell in a UITableView, then its not possible in the horizontal scroller.

The reusable cells property for a table view is provided by the system and it not applicable for horizontal scroller.

You have to write on your own logic in order to achieve it, perhaps! Its a good question though. Will be tuned to other answers just in case if anything is possible.