unselect checkmarks into Collectionview in swift4

Question

I am showing collocation view with multiple checkmarks in main view controller.its working fine

after select checkmarks data showing into next view controller. it is also working. when i back to main view controller which I selected check marks are not unchecked. how to uncheck selected checkmarks.

I used this reference https://github.com/maximbilan/CheckMarkView

@IBOutlet weak var checkMarkViews: CheckMarkView!


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


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

        let row = indexPath.row

        cell.CoutnryImages.downloadImageFrom(link: imagesarray[row] , contentMode: .scaleToFill)

        cell.countrynmae.text = itemsarray[row]

        cell.checkMarkViews.setNeedsDisplay()

      return cell

    }


    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        let cell = CollectionView.cellForItem(at: indexPath) as! CustomCollectionViewCell

        var indexpathvalues = indexPath.row   

        cell.checkMarkViews.checked = !cell.checkMarkViews.checked

        if cell.checkMarkViews.checked == true
        {

           PassedID.append(idarray[indexpathvalues])
            _selectedcell.add(indexpathvalues)

        }
        else
        {
        if PassedID.isEmpty
            {
                print("no Item found ")
            }
            else
            {
                 _selectedcell.remove(indexpathvalues)
                PassedID.removeLast()
            }

        }

    }

    @IBAction func Addbutton(_ sender: UIBarButtonItem) {

              performSegue(withIdentifier: "next", sender: self)

    }

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        let vc = segue.destination as? nextViewController

        vc?.arrayvalues = self.PassedID

        _ = navigationController?.popViewController(animated: true)       

    }

how to uncheck the multiple selection after back to main view controller  

Answer 1

override func viewWillAppear(_ animated: Bool) {

    // get visible cells and un check them

    let visibleCell = cc.visibleCells as! [CustomCollectionViewCell]

    for cell in visibleCell
    {
        // un check here

    }

}

Answer 2

In order to synchronize your cells with actual selection state, you need to store it. Ideally, you will need model here, which will contain state (like isSelected or something). But in the listed code would be just enough store Set (or Array , doesn't actually matter) of selected cells' [IndexPath] .

Once a user selects/deselects some cell you should update your collection (append/remove appropriate IndexPath ).

In func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell method you should update your checkmarks' state.