 
         let itemCounts = allItemAttributes.count
         var index = 0
-        while(index < itemCounts){
+        while index < itemCounts {
             let rect1 = allItemAttributes[index].frame
             index = min(index + unionSize, itemCounts) - 1
             let rect2 = allItemAttributes[index].frame

            }

            attributes = UICollectionViewLayoutAttributes(forCellWithIndexPath: indexPath)
            attributes.frame = CGRectMake(xOffset, CGFloat(yOffset), calculatedItemWidth, itemHeight)
            itemAttributes.append(attributes)

            allItemAttributes.append(attributes)
            if isFullWidth && columnCount > 1 {
                columnHeights[0] = Double(CGRectGetMaxY(attributes.frame))
                columnHeights[1] = Double(CGRectGetMaxY(attributes.frame))
            }
            else {
                columnHeights[currentColumIndex] = Double(CGRectGetMaxY(attributes.frame))
            }
        }


            return collectionView!.delegate as? StreamCollectionViewLayoutDelegate
        }
    }
    var columnHeights = [CGFloat]()
    var sectionItemAttributes = [[UICollectionViewLayoutAttributes]]()
    var allItemAttributes = [UICollectionViewLayoutAttributes]()
    var unionRects = [CGRect]()
