Updating a single cell in CollectionView using Swift : I am new to Swift. 
I have a problem with updating a single cell when using CollectionView.
When I click on a label, I want the label will change the value to a different number which I can assign manually.
I appreciate any help

Code:

     override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        //return nameArray.count;
        return 81;
    }
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell=collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! CollectionViewCell;
        
        switch(flattened[indexPath.item]){
        case 1:
            cell.labelText.text="1";
        case 2:
           cell.labelText.text="2";
        case 3:
            cell.labelText.text="3";
        case 4:
            cell.labelText.text="4";
        case 5:
            cell.labelText.text="5";
        case 6:
            cell.labelText.text="6";
        case 7:
            cell.labelText.text="7";
        case 8:
            cell.labelText.text="8";
        case 9:
            cell.labelText.text="9";
        default:
            cell.labelText.text="0";
            //print(indexPath.item)
            
        }
        
        return cell;
    }
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        
    }
    
Picture

[When I run my code][1]


  [1]: https://i.stack.imgur.com/4bOS5.jpg