CODEWITHSUNDEEP
iosobjective-ccocoa-touch
aLFaRSi
aLFaRSi

Reputation: 559

UITableView Scrolling Freeze when loading images from server

I'm using this code for loading my images in a UITableView using custom cell 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

static NSString *CellIdentifier = @"CustomCell";

CustomCell *cell = (CustomCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil) {

    NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil];
    for (id currentObject in topLevelObjects) {
        if ([currentObject isKindOfClass:[CustomCell class]]) {
            cell = (CustomCell *) currentObject;
            break;
        }
    }

    NSString *tempString = [arrayThumbs objectAtIndex:indexPath.row];
    NSURL *imageURL = [NSURL URLWithString:tempString];
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
    UIImage *image = [UIImage imageWithData:imageData];
    cell.img.image = image;

}

return cell;
}

with the above code, there is no problem when scrolling up and down, but the images doesn't show correctly, some images are repeated in the table , example for that if the array holds 10 images from 1 to 10 and the array is correct in the order, the images i get in the table something like 1 , 2 , 3 , 4 , 3 , 3 , 1 , 10 , 8 , 9

but when i use this code

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

static NSString *CellIdentifier = @"CustomCell";

CustomCell *cell = (CustomCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil) {

    NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil];
    for (id currentObject in topLevelObjects) {
        if ([currentObject isKindOfClass:[CustomCell class]]) {
            cell = (CustomCell *) currentObject;
            break;
        }
    }

}

NSString *tempString = [arrayThumbs objectAtIndex:indexPath.row];
    NSURL *imageURL = [NSURL URLWithString:tempString];
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
    UIImage *image = [UIImage imageWithData:imageData];
    cell.img.image = image;

return cell;
}

the images are ordered fine and no duplicates but when i scroll to the bottom of the table then scrolling back to the top the table freeze for 2 or 3 seconds

any idea how to solve this ?

the array contain links for the images like http://www.website.com/image.jpg

custom cell contain IBOutlet UIImageView 60x60 and the images that loads from the server are also 60x60

Upvotes: 1

Views: 2581

Answers (1)

lu yuan
lu yuan

Reputation: 7227

try the following code to download the image in the thread.

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    NSString *tempString = [arrayThumbs objectAtIndex:indexPath.row];
    NSURL *imageURL = [NSURL URLWithString:tempString];
    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
    UIImage *image = [UIImage imageWithData:imageData];
    dispatch_async(dispatch_get_main_queue(), ^{
      cell.img.image = image;
    });
});

Upvotes: 8

Related Questions