Load image to a tableView from URL iphone sdk

Question

I have tableView and need to load image from URL. I have an array that contains the URLs of images and when the page loads I need to load all the images into the tableview. Note that, not from a single URL, have an array with different URLs. How can I implement that? Please help

Thanks.

Decision

The best solution I found: https://mcmap.net/q/151665/-asynchronous-downloading-of-images-for-uitableview-with-gcd! – Regality

Answer 1

You can use GCD to load images in background thread, like this:

//get a dispatch queue
dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //this will start the image loading in bg
    dispatch_async(concurrentQueue, ^{        
        NSData *image = [[NSData alloc] initWithContentsOfURL:imageURL];

        //this will set the image when loading is finished
        dispatch_async(dispatch_get_main_queue(), ^{
            imageView.image = [UIImage imageWithData:image];
        });
    });

Hi. But you probably need to add a dispatch_release(concurrentQueue); to be sure no leak. – Franck Aug 25 at 19:43

Wivern

Hi. But you probably need to add a dispatch_release(concurrentQueue); to be sure no leak. – Putput

Side question: do you need @autorelease pool when using dispatch_async? – Neau

Answer 2

You can use Lazy Loading when you want to download Images from internet

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
   //All you reusable cell implementation here.
   //Since your Images sizes differ. Keep a custom Imageview

    if(![imagesForCategories containsObject:indexPath])
    {    
        customImageView.image = [UIImage imageNamed:@"default-image.png"];
        NSMutableArray *arr = [[NSArray alloc] initWithObjects:[imageUrlArray objectAtIndex:indexPath.row],indexPath, nil];
        [self performSelectorInBackground:@selector(loadImageInBackground:) withObject:arr];
        [arr release];
    }
    return cell;
}

- (void) loadImageInBackground:(NSArray *)urlAndTagReference 
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSURL *imgUrl=[[NSURL alloc] initWithString:[urlAndTagReference objectAtIndex:0]];
    NSData *imgData = [NSData dataWithContentsOfURL:imgUrl];
    UIImage *img = [UIImage imageWithData:imgData];
    [imgUrl release]; 
    NSMutableArray *arr = [[NSMutableArray alloc ] initWithObjects:img,[urlAndTagReference objectAtIndex:1], nil  ];
    [self performSelectorOnMainThread:@selector(assignImageToImageView:) withObject:arr waitUntilDone:YES];
    [arr release];
    [pool release];
}

- (void) assignImageToImageView:(NSMutableArray *)imgAndTagReference
{
    [imagesForCategories addObject:[imgAndTagReference objectAtIndex:1]];
    UITableViewCell *cell = [celebCategoryTableView cellForRowAtIndexPath:[imgAndTagReference objectAtIndex:1]];
    UIImageView *profilePic = (UIImageView *)[cell.contentView viewWithTag:20];
    profilePic.image = [imgAndTagReference objectAtIndex:0];

}

Dinky

You can also see this apple sample code for lazyloading developer.apple.com/library/ios/#samplecode/LazyTableImages/… – Dinky

Answer 3

You can use SDWebImage which permits very easy and speed loading of images in UITableView.
https://github.com/rs/SDWebImage

Tingly

Answer 4

Try this code,imagearray contains urls of image

-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSData* imageData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString: [imagearray objectAtIndex:row]]];
    UIImage* image = [[UIImage alloc] initWithData:imageData];


    cell.imageView.image =image;
    return cell;
}

Dg

This will freeze Interface while image downloading – Housemother

thanks, and its working fine. But the image sizes are different. – Decision

and also, running slowly, is there any idea to make it run fast, sometimes its freezing. – Decision

If there is large amount of data(images),you need to download it asynchronously...Chk this link markj.net/iphone-asynchronous-table-image – Dg

Answer 5

You need to create your custom cell for lazy loading. This will allow you to download images correctly and without freezing. Here is nice example how to do this: Asynch image loading

Housemother

Answer 6

With afnetworki, it is too easy.

//afnetworking

#import "UIImageView+AFNetworking.h"

 [cell.iboImageView setImageWithURL:[NSURL URLWithString:server.imagen] placeholderImage:[UIImage imageNamed:@"qhacer_logo.png"]];

Dogwatch