I have this array: 

```
media = [  
        [UIImage(named: "1.png")!,UIImage(named: "14.png")!,UIImage(named: "2.png")!],
        [UIImage(named: "3.png")!,UIImage(named: "15.png")!,UIImage(named: "4.png")!],
        [UIImage(named: "5.png")!,UIImage(named: "16.png")!,UIImage(named: "6.png")!],
        [UIImage(named: "7.png")!,UIImage(named: "17.png")!,UIImage(named: "8.png")!],
        [UIImage(named: "9.png")!,UIImage(named: "18.png")!,UIImage(named: "10.png")!],
        [UIImage(named: "11.png")!,UIImage(named: "19.png")!,UIImage(named: "12.png")!],
        [UIImage(named: "13.png")!,UIImage(named: "21.png")!,UIImage(named: "47.png")!]
    ]

```

Also I have a `collectionView`:

```
func numberOfSections(in collectionView: UICollectionView) -> Int {
        return media.count
    }

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

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! MasterViewCell

        cell.thisImage.image = media[indexPath.section][indexPath.row]

        return cell
    }

```

But I have a problem. When I scroll my `collectionView` my app freezing. But when I scroll for all section and continue scroll next. My app not freezing.

How to fix it?