Iphone UIScrollView Lazy Image Loading.

In Your *.H File put this code

@interface ScrollviewLazyLoadingViewController : UIViewController

<UIScrollViewDelegate, thumbImageViewDelegate>

{

    IBOutlet UIScrollView *Scorll_View;

    BOOL isDragging_msg,isDecliring_msg;

    NSMutableDictionary *dicImages_msg;

    NSMutableArray *ImgesName;  

}

@property(nonatomic,retain) NSDictionary *results;

@property(nonatomic,retain) NSMutableArray *ImgesName;

-(void)DownLoad:(NSNumber *)path;

-(void) reloadScrolview;

@end

Now Add this code in your  class.m File

- (void)viewDidLoad

{

    [super viewDidLoad];

    [Scorll_View setContentSize:CGSizeMake(300, 1200)];

    Scorll_View.delegate = self;

    dicImages_msg = [[NSMutableDictionary alloc] init];

    NSURLRequest *Projrequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"Your Image Store Link"]];

    NSData *response = [NSURLConnection

                        sendSynchronousRequest:Projrequest

                        returningResponse:nil error:nil];

    NSString *json_string = [[NSString alloc]

                             initWithData:response encoding:NSUTF8StringEncoding];

    SBJSON *jsonParser = [SBJSON new];

   self.results = [jsonParser objectWithString:json_string error:nil];

    NSLog(@"Dictionary : %@", results);

    self.ImgesName = [results valueForKey:@"images"];

    [self reloadScrolview];

}

-(void) reloadScrolview

{

    int x=10;

    int y=0;

    for(int i=0; i<[self.ImgesName count];)

    {

        for (int k=0; k<2; k++) 

        {

            if(i< [self.ImgesName count])

            {

                thumbImageView *imgView = [[thumbImageView alloc] initWithFrame:CGRectMake(x, y, 75,75)];

                if([dicImages_msg valueForKey:[self.ImgesName objectAtIndex:i]])

                {

                    imgView.image = [dicImages_msg valueForKey:[self.ImgesName objectAtIndex:i]];

                }

                else

                {

                    if(!isDragging_msg && !isDecliring_msg)

                    {

                       [dicImages_msg setObject:[UIImage imageNamed:@"Placeholder.png"] forKey:[self.ImgesName objectAtIndex:i]];

                        [self performSelectorInBackground:@selector(DownLoad:) withObject:[NSNumber numberWithInt:i]];

                    }

                    else

                    {

                        imgView.image = [UIImage imageNamed:@"Placeholder.png"];

                    }

                }

                imgView.userInteractionEnabled = YES;

                [imgView setDelegate:self];

                imgView.tag = i;

                imgView.exclusiveTouch = YES;

                imgView.clipsToBounds = NO;

                imgView.opaque = YES;

                [imgView.layer setBorderWidth: 2.0];

                [Scorll_View addSubview:imgView];

                x+=120;

                i++;

            }

        }

        x=10;

        y+=80;

        

    }

}

-(void)DownLoad:(NSNumber *)path

{

NSAutoreleasePool *pl = [[NSAutoreleasePool alloc] init];

    int index = [path intValue];

NSString *Link = [NSString stringWithFormat:@"%@%@",[results valueForKey:@"imageurl_middle"],[self.ImgesName objectAtIndex:index]];

UIImage *img = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:Link]]]; 

    if(img)

    {

        [dicImages_msg setObject:img forKey:[self.ImgesName objectAtIndex:index]];

    }

[self performSelectorOnMainThread:@selector(reloadScrolview) withObject:path waitUntilDone:NO];

[pl release];

}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate

{

isDragging_msg = FALSE;

    [self reloadScrolview];

}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

{

isDecliring_msg = FALSE;

[self reloadScrolview];

}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView

{

isDragging_msg = TRUE;

}

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView

{

isDecliring_msg = TRUE;

}