How to use nscache to download image from api.? - ios

Question

I have a UIImageview in UICollectionview cell and parse the image data from api and add to UIImageview. Now everything is going perfect but there is some problem I face during scroll down, when I tried to scroll UICollectionview cell its going hang.
Now I need to use NSCache to download image and than add it to UIImage, but I am unable to do this task I am stuck somewhere in my code, I don't know where. Please look at my code.
-(UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
OneTimeCell *cell = (OneTimeCell*)[collectionView dequeueReusableCellWithReuseIdentifier:#"cell" forIndexPath:indexPath];
cell.selected = YES;
[collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
cell.productname.text = [[productname objectAtIndex:indexPath.row] objectForKey:#"product_name"];
cell.productnumber.text = [[productname objectAtIndex:indexPath.row] objectForKey:#"id"];
NSString *image = [[productname objectAtIndex:indexPath.row] objectForKey:#"image" ];
NSLog(#"image %#", image);
NSURL *baseURL = [NSURL URLWithString:#"http://dev1.brainpulse.org/ecoware1//app/webroot/img/uploads/Product/thumb/"];
NSURL *url = [NSURL URLWithString:image relativeToURL:baseURL];
NSData * imageData = [NSData dataWithContentsOfURL:url];
UIImage * productimage = [UIImage imageWithData:imageData];
NSURL *absURL = [url absoluteURL];
NSLog(#"absURL = %#", absURL);
if (productimage) {
cell.productimage.image = productimage;
}
else
{
cell.productimage.image = [UIImage imageNamed:#"icon_1.png"];
[self.imageDownloadingQueue addOperationWithBlock:^{
NSURL *url = [NSURL URLWithString:image relativeToURL:baseURL];
NSData * imageData = [NSData dataWithContentsOfURL:url];
UIImageView *image = nil;
if (image) {
[self.imageCache setObject:image forKey:imageData];
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
OneTimeCell *cell =[collectionView cellForItemAtIndexPath:indexPath];
if (cell) {
cell.productimage.image = image;
}
}];
}
}];
}
return cell;
}

Answer 1

in your code line 10 you fetching image on mainthread that is why your cell got stuck . . .Please replace that code with this one
Replace this code
NSString *image = [[productname objectAtIndex:indexPath.row] objectForKey:#"image" ];
NSLog(#"image %#", image);
NSURL *baseURL = [NSURL URLWithString:#"http://dev1.brainpulse.org/ecoware1//app/webroot/img/uploads/Product/thumb/"];
NSURL *url = [NSURL URLWithString:image relativeToURL:baseURL];
NSData * imageData = [NSData dataWithContentsOfURL:url];
UIImage * productimage = [UIImage imageWithData:imageData];
NSURL *absURL = [url absoluteURL];
NSLog(#"absURL = %#", absURL);
With This one
NSString *image = [[productname objectAtIndex:indexPath.row] objectForKey:#"image" ];
NSLog(#"image %#", image);
NSURL *baseURL = [NSURL URLWithString:#"http://dev1.brainpulse.org/ecoware1//app/webroot/img/uploads/Product/thumb/"];
NSURL *url = [NSURL URLWithString:image relativeToURL:baseURL];
dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(q, ^{
NSData * imageData = [NSData dataWithContentsOfURL:url];
dispatch_async(dispatch_get_main_queue(), ^{
UIImage * productimage = [UIImage imageWithData:imageData];
});
});

Answer 2

NSURL *url = #"................";
ImageRequest *request = [[ImageRequest alloc] initWithURL:url];
UIImage *image = [request cachedResult];
if (image) {
// Set the image if exist
} else {
[request startWithCompletion:^(UIImage *image, NSError *error) {
dispatch_async(dispatch_get_main_queue(), ^{
if(image) {
cell.productimage.image = productimage;
}else {
// Set any placeholder image here.......
}
});
}];
}

Answer 3

NSString *image = [[productname objectAtIndex:indexPath.row] objectForKey:#"image" ];
NSLog(#"image %#", image);
NSURL *baseURL = [NSURL URLWithString:#"http://dev1.brainpulse.org/ecoware1//app/webroot/img/uploads/Product/thumb/"];
NSURL *url = [NSURL URLWithString:image relativeToURL:baseURL];
dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(q, ^{
//NSData * imageData = [NSData dataWithContentsOfURL:url];
NSOperationQueue *queue = [[NSOperationQueue alloc] init];
[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:url] queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
{
if(data)
{
dispatch_async(dispatch_get_main_queue(), ^{
UIImage * productimage = [UIImage imageWithData:data];
});
}
}];
});