Display images from json (url of images) vlaue to CollectionView - objective-c

Question

hi i tried to display images from json to CollectionView .
my code is...
NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:#"http://zoo.com/jh/image.php"]];
[request setHTTPMethod:#"GET"];
[request setValue:#"application/json;charset=UTF-8" forHTTPHeaderField:#"content-type"];
NSError *err;
NSURLResponse *response;
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&err];
NSDictionary *jsonArray = [NSJSONSerialization JSONObjectWithData:responseData options: NSJSONReadingMutableContainers error: &err];
NSArray *headlines=[jsonArray1 objectForKey:#"image_gallery"];
for (int i=0;i<[headlines count]; i++)
{
NSString *moblinks=[[headlines objectAtIndex:i]objectForKey:#"image_url"];
[self.itemshowdetailsAr objectAtIndex:moblinks];
NSLog(#"%#",moblinks);
}
and my result in console
2014-06-20 15:05:27.005 Collection[3945:60b] http://xxxxxx/jh/ju_image/gal_1.jpg
2014-06-20 15:05:27.007 Collection[3945:60b] http://xxxxxx/jh/ju_image/gal_2.jpg
2014-06-20 15:05:27.007 Collection[3945:60b] http://xxxxxx/jh/ju_image/gal_3.jpg
2014-06-20 15:05:27.007 Collection[3945:60b] http://xxxxxx/jh/ju_image/gal_4.jpg
2014-06-20 15:05:27.008 Collection[3945:60b] http://xxxxxx/jh/ju_image/gal_5.jpg
2014-06-20 15:05:27.008 Collection[3945:60b] http://xxxxxx/jh/ju_image/gal_6.jpg
my collectionview code
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"Cell" forIndexPath:indexPath];
NSString *ImageURL =[self.itemshowdetailsAr objectAtIndex:indexPath.row];
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:ImageURL]];
cell.imageView.image = [UIImage imageWithData:imageData];
cell.imageView.userInteractionEnabled=YES;
cell.imageView.contentMode = UIViewContentModeScaleToFill;
// cell.imageView.tag=i-1;
return cell;
}
but i got empty Collection View only.where i made mistake?i got array of url in console but cell is not displaying images.

Answer 1

By the looks of it you're trying to download image on the main thread and I'm guessing that the UI might be freezing while network requests are processed. Instead load the images asynchronously and away from the main thread by doing something like
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"Cell" forIndexPath:indexPath];
NSURLSession *session=[NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
[[session dataTaskWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:[self.itemshowdetailsAr objectAtIndex:indexPath.row]]] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
cell.imageView.image = [UIImage imageWithData:data];
cell.imageView.userInteractionEnabled=YES;
cell.imageView.contentMode = UIViewContentModeScaleToFill;
}];
}] resume];
return cell;
}
The NSURLSession task will run away from the main thread. The completion handler will be called when the imageData has been downloaded. At this point an operation is added to the main thread to update the imageView within your collectionViewCell.