CODEWITHSUNDEEP
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SamehDos
SamehDos

Reputation: 1203

UITableview with images scroll very slow

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;
}

Upvotes: 4

Views: 3434

Answers (6)

CalixJumi
CalixJumi

Reputation: 377

I had the same issue and it was corrected by not using the cornerRadius property. Then we used a background image with the form of the cell.

Upvotes: 1

Nik Burns
Nik Burns

Reputation: 3423

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

Upvotes: 8

Nikita Ivaniushchenko
Nikita Ivaniushchenko

Reputation: 1435

Configuring of all general appearance should be in if (cell == nil) {} Only setting unique stuff, such as title and so on should be outside. Also, if your cell's background is simple (such as gradient), use the QuartzCore to draw it or use CAGradientLayer as sublayer to contentView's layer.

Upvotes: 0

MiKL
MiKL

Reputation: 1850

Have you run the profiler on your code? As Nik burns mentioned you should load your images from the network asynchronously using either GCD or NSOperation. You can watch the Harvard iTunesU video for NSOperation: it will give you a clear example with good explanations.

And you should definitely run the profiler to see where you are spending the most time. A cell with a few images should load fast.

Note that some operations on the cell which could be done at initialization (such as setting the background color on a cell) can end-up costing you a lot of performance if you do them repeatedly.

Als if you have a special layout for your cell you should subclass the UITableViewCell and implement the layoutSubviews method (don't forget to call super). Doing lots of work in the tableViewDataSourceDelegate (and forcing relayout as you do) can really be inefficient.

But again: run the profiler

Upvotes: 1

Kheldar
Kheldar

Reputation: 5389

I wonder why you create your image inside the viewcell code. Can't you create it once for the whole class and then position it into the UIView on demand?

Upvotes: 0

Padavan
Padavan

Reputation: 1074

Maybe your list_bg_01.png image is big? This method take a lot of memory, you should use it only when patternimage really small and simple, in other conditions better to use UIImageView with image as background view.

Upvotes: 1

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