NsoperationQueue Cancel all operations is not cancelled until it finishes the operation

Question

In my view i have image view, the data for image view comes form Url, the images are around 1-3 MB . If the user Swipes then i want to load the next image, Every thing works fine if swiped slowly, But when i swiped Fastly I want to Cancel the previous operation and start with new url.

For Ex. if user swipes 4 times if the operations for 2nd and 3rd images is in the middle, i want to cancel those and start downloading 4 th image

But now In the place of 4th image I’m getting first 2nd image follows 3rd and then 4 th image appears.

Here is my sample code

- (void)handleSwipeLeft:(UISwipeGestureRecognizer *)aSwipeGestureRecognizer {


    [BackgroundOperation cancelAllOperations];  // To cancel previous one 


    [self performSelector:@selector(LoadImage) withObject:nil afterDelay:0.1];


}

-(void)LoadImage
{
    BackgroundOperation=[[NSOperationQueue alloc]init];  


    imgvww.image=[UIImage imageNamed:@"loader.png"]; // Place holder    till download finishes 


   [BackgroundOperation addOperationWithBlock:^
     {
         UIImage *img=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[[self.ItemDetails objectAtIndex:0] objectForKey:@"ImageUrl"]]]];  // Getting data from URL 

         [[NSOperationQueue mainQueue] addOperationWithBlock:^{


             imgvww.image=img;  //Adding to image view after completion 


         }];

     }];
 }

Thank you.