Uiscrollview lazy loading

Question

I have got all images of iphone using AssetsLibrary.I am passing UIImage object in imageview and display images in scrollview. There are more than 200 images in iphone and i

Answer 1

You can use GCD block and grand central dispatch. in your .h file declare it

dispatch_queue_t imageQueue_;

Create an NSmutableDictionary

@property (nonatomic, strong) NSMutableDictionary *thumbnailsCache;

Use below Code to Show image.

NSString *thumbnailCacheKey = [NSString stringWithFormat:@"cache%d",imageIndex];

    if (![[self.thumbnailsCache allKeys] containsObject:thumbnailCacheKey]) {

        // thumbnail for this row is not found in cache, so get it from remote website
        __block NSData *image = nil;
        dispatch_queue_t imageQueue = dispatch_queue_create("queueForCellImage", NULL);
        dispatch_async(imageQueue, ^{
            NSString *thumbnailURL = [NSString stringWithFormat:@"%@",deal_Class.deal_imageUrl];
            image = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:@"Your URL"]];
            dispatch_async(dispatch_get_main_queue(), ^{



              imageView.image = [UIImage imageWithData:image];

                if (image) {
                    [self.thumbnailsCache setObject:image forKey:thumbnailCacheKey];
                }


            });
        });

     //   dispatch_release(imageQueue);


    } else {

        // thumbnail is in cache
        NSData *image = [self.thumbnailsCache objectForKey:thumbnailCacheKey];
        dispatch_async(dispatch_get_main_queue(), ^{
            imageview.image = [UIImage imageWithData:image];
        });
    }