Multiple GCD request in a scrollView - objective-c

Question

I have a scrollView which i load images into while scrolling,and every time it has only 3 pages with images(current previous next ) .
It works great ,and the memory consumption is low (30-40M) for the iPad .
Problem is, that when i scroll fast(no paging enable), i get a memory warning, even that the memory is low.
I discovered that this is because of multiple GCD requests at once .
What can be done, in order to eliminate this from happen ?
One solution i could think of, is to start loading only when scroll view is decelerating , but i am afraid that the UX will be bad with this(now it looks great) ,
Another one, is using NSOperation for this- which is a higher level and might be better ?
Another one, is to use AutoreleasePool for the thread request-which i saw in a few articles.
What is the best approach for this ?
Here is the loader, that happens while scrolling (to relevant pages):
[self downloadImageWithURL:userUrl completionBlock:^(BOOL succeeded, NSData *tdata)
{
if (succeeded)
{
//load back
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^
{
UIImage *image=[UIImage imageWithData:tdata scale:1];
if (image)
{
UIGraphicsBeginImageContextWithOptions(image.size, NO, image.scale);
[image drawAtPoint:CGPointZero];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
dispatch_async(dispatch_get_main_queue(), ^
{
//LOAD EASY
[UIView transitionWithView:view
duration:0.1f
options:UIViewAnimationOptionTransitionCrossDissolve
animations:^
{
view.image=nil;
view.image=image;
}
completion:nil];
});
image=nil;
});
}
}];
}

Answer 1

I found a great solution that works great for me, i have an array of all what is being loading right now, and i have checked when this array size causing troubles . When user scrolls i check its size, and when the size exceeded a certain size, i just stop the scroller from scrolling fast. This happens usually when the user is scrolling too fast.
CGRect frame=scroller.frame;
frame.origin.y=scroller.contentOffset.y-1.0;
if ([imagesAreLoading count]>10 )//too many requests has being made.
[scroller scrollRectToVisible:frame animated:YES];
Hope it helps other people.