VansFannel VansFannel - 1 month ago 17
iOS Question

Loading an image into UIImage asynchronously

I'm developing an iOS 4 application with iOS 5.0 SDK and XCode 4.2.

I have to show some post blogs into a UITableView. When I have retreived all web service data, I use this method to create an UITableViewCell:

- (BlogTableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString* cellIdentifier = @"BlogCell";

BlogTableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];

if (cell == nil)
{
NSArray* topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"BlogTableViewCell" owner:nil options:nil];

for(id currentObject in topLevelObjects)
{
if ([currentObject isKindOfClass:[BlogTableViewCell class]])
{
cell = (BlogTableViewCell *)currentObject;
break;
}
}
}

BlogEntry* entry = [blogEntries objectAtIndex:indexPath.row];

cell.title.text = entry.title;
cell.text.text = entry.text;
cell.photo.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:entry.photo]]];

return cell;
}


But this line:

cell.photo.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:entry.photo]]];


it is so slow (entry.photo has a http url).

Is there any way to load that image asynchronously? I think it is difficult because tableView:cellForRowAtIndexPath is called very often.

Answer

Take a look at SDWebImage:

https://github.com/rs/SDWebImage

It's a fantastic set of classes that handle everything for you.

Tim

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