UITableview with images scroll very slow

Question

I have a UITableView which downloads its tableviewcells images from a server.

I observed that the table scroll very slowly.

I thought that this might be due to the downloading, but I have realized that the table still scroll slow after download has finished and the image icon size is very less.

The code:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    btnBack.hidden = FALSE;

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil)
    {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;

        /////////////////////   Cell other accessories    /////////////////////
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
        cell.backgroundColor = [UIColor clearColor];
//        cell.backgroundView = [[UIImageView alloc] initWithImage:[[UIImage imageNamed:@"list_1.jpg"] stretchableImageWithLeftCapWidth:0.0 topCapHeight:5.0]];
//        cell.selectedBackgroundView = [[UIImageView alloc] initWithImage:[[UIImage imageNamed:@"list_2.jpg"] stretchableImageWithLeftCapWidth:0.0 topCapHeight:5.0]];

        /////////////////////   Cell Title    /////////////////////
        cell.textLabel.font = [UIFont fontWithName:@"Noteworthy" size:17.0];
        cell.textLabel.font = [UIFont boldSystemFontOfSize:17.0];
        cell.textLabel.textColor = [UIColor blackColor];
        cell.textLabel.highlightedTextColor = [UIColor blackColor];


    }

        /////////////////////   Cell Title    /////////////////////
        cell.textLabel.text = [NSString stringWithFormat:@"     %@", [test.arrTitle objectAtIndex:indexPath.row]];


        /////////////////////   Cell Image    /////////////////////


        NSString *Path;
        Path = [NSString stringWithFormat:@"http://%@",[test.arrImages objectAtIndex:indexPath.row]];
        NSLog(@"image-->%@",[test.arrImages objectAtIndex:indexPath.row]);
        NSString *strImage = Path;
        NSURL *url4Image = [NSURL URLWithString:strImage];    
        NSData *data = [NSData dataWithContentsOfURL:url4Image];
        image =[[UIImage alloc] initWithData:data];
        cell.imageView.image =image;
        [image release];

        return cell;
}

Answer 1

You should look to use an NSOperationQueue to handle lazy loading of images and a custom tableviewcell.
Google for tweetie custom tableviewcell That should set you in the right direction.

Apple has a sample project for downloading images in tableViews: LazyTableImages