var imagesArray:[[String]] = []

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return imagesArray[section].count
}

func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {

    return imagesArray.count
}

func insertNewRow()
{
    self.collectionView.performBatchUpdates({ () -> Void in

        self.imagesArray.append(["Real2.jpg","cat3.jpg","Man1.png"])

        let firstIndexPath  = NSIndexPath(forItem: 0, inSection: 2)
        let secondIndexPath = NSIndexPath(forItem: 1, inSection:2)
        let thirdIndexPath = NSIndexPath(forItem: 2, inSection:2)
        self.collectionView.insertSections(NSIndexSet(index: 2))
        self.collectionView.insertItemsAtIndexPaths([firstIndexPath,secondIndexPath,thirdIndexPath])

        }) { (finished) -> Void in

    }
}