title: Cell spacing in UICollectionView minimumInteritemSpacing
body: <p>How to do set cell spacing in a section of UICollectionView?  UICollectionView there is a property <code>minimumInteritemSpacing</code>, I need to set  1.0 still it not work. And I implemented the delegate method. </p>
  
  <pre><code>- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
    {
       return 1.0;
    }
  </code></pre>