This is how I tried to implement ipmcc's answer to this question http://stackoverflow.com/questions/19540713/imagewithcgimage-gcd-memory-issue I added the asset library to make sure that the asset object get released and it is not retained somewhere else.

gistfile1.m

    NSURL *asseturl = [_asset valueForProperty:ALAssetPropertyAssetURL];
    __block ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
        
    [assetslibrary assetForURL:asseturl resultBlock:^(ALAsset *asset) {
        
        __block ALAsset *weakAsset = [asset retain];
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
            
            @autoreleasepool {
                
                ALAssetRepresentation* rep = [weakAsset defaultRepresentation];
                CGImageRef iref = [rep fullScreenImage];
                UIImage* image = [UIImage imageWithCGImage:iref
                                                     scale:[rep scale]
                                               orientation:UIImageOrientationUp];
                
                __block UIImage* weakImage = [image retain];
                
                [weakAsset release];
                [assetslibrary release];

                dispatch_async(dispatch_get_main_queue(), ^(void) {
                    if (weakImage) {
                        [self.imageView setImage:weakImage];
                        [weakImage release];
                    }
                });
            }
        });
    } failureBlock:^(NSError *error) {
        
    }];