Assertion error in - [UICollectionViewData layoutAttributesForSupplementaryElementOfKind: atIndexPath:]

I am getting this error in the collection view. I have implemented this method and I am returning the footer for the last section.

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
{
    if (section == LAST_SECTION_INDEX) 
    {
        return CGSizeMake(self.view.width, 50);
    }

    return CGSizeZero;
}

      

        
        
        
      

    

and in viewForSupplementaryElementOfKind

which I have implemented like this: CollectionViewFooter

is a subclass of UICollectionReusableView

class

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    CollectionViewFooter *footer = [self.collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:FooterIdentifier forIndexPath:indexPath];
      return footer;
}

      

        
        
        
      

    

when data collection reloads it crashes and gives me this error.

Assertion error in - [UICollectionViewData layoutAttributesForSupplementaryElementOfKind: atIndexPath:]

I am stuck here. Can anyone please help?

Thank.