UIImage setImage not work, sometimes - ios

Question

I have a class variable imageView of class UIImageView and a button.
The array of images is loaded from the Gallery by using Assets.
When the loading of all images is done, I show the first image:
- (void)showImage
{
if ([images count] > 0)
[self.imageView setImage:[images objectAtIndex:0]];
currentPage = 0;
}
Everything is good so far,
But when I tap the button with following action:
- (IBAction)buttonNext:(id)sender {
NSLog(#"images array %#", images );
if (currentPage < [images count]-1)
{
NSLog(#"next currentPage %d %d %#",currentPage, [images count],[images objectAtIndex:currentPage])
currentPage++;
[self.imageView setImage:[images objectAtIndex:currentPage]];
}
}
no image replacement takes place. The imageView stucks the previous image.
I debugged the array of images:
images array (
"<UIImage: 0xb38cec0>",
"<UIImage: 0xb0f8280>",
"<UIImage: 0xb063360>",
"<UIImage: 0xb0660a0>"
)
EDIT
The code which loads the images:
-(void)loadImage:(NSString*)url
{
ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
{
ALAssetRepresentation *rep = [myasset defaultRepresentation];
CGImageRef iref = [rep fullResolutionImage];
if (iref) {
UIImage *largeImage = [UIImage imageWithCGImage:iref];
CGSize size=CGSizeMake(400, 500);//set the width and height
UIGraphicsBeginImageContext(size);
[largeImage drawInRect:CGRectMake(0,0,size.width,size.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
//here is the scaled image which has been changed to the size specified
UIGraphicsEndImageContext();
[images addObject:newImage];
if ([images count] == [pages count])
[self showImage];
}
};
ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror)
{
NSLog(#"Can't get image - %#",[myerror localizedDescription]);
};
NSURL *asseturl = [NSURL URLWithString:url];
[assetslibrary assetForURL:asseturl
resultBlock:resultblock
failureBlock:failureblock];
}
- (void)viewWillAppear:(BOOL)animated
for(NSDictionary* a in pages)
{
if ([a objectForKey:#"iospath"] != nil)
[self loadImage:[document objectForKey:#"iospath"]];
}
pages is an array loaded in viewDidLoad. The images are there. Why I can not show'em?
Regards