Invisible cells of UICollectionView are not deselected - Swift - swift

Question

I have in my swift app two collection views. One which is a functions categories and another one which is the functions. The first one works as a filter to the second one. If I select "Cat1" then only functions with tag "Cat1" are displayed. This works great.
The functions categories collectionview is horizontal and I need to scroll to see all the cells. My issue/problem is already mentioned in another topics but I can not find the right anwser or technique.
Issue: If I select a category, the cell's background changes, fine. If now I scroll completely to the end of the collectionview and select the last cell, this one change as selected the the first one (previously selected) is not deselected.. I know that is a problem with reused cell but no idea how to manage that. Below my code :
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
// Working with functions categories collection view
if collectionView == self.functionsCategoriesCollectionView {
let cell = collectionView.cellForItem(at: indexPath) as! DevicePageFunctionsCategoriesCVCell
cell.isHidden = false
cell.cellView.isHidden = false
cell.isSelected = true
cell.cellView.clipsToBounds = true
cell.cellView.layer.cornerRadius = 25
cell.cellView.addGradiant(colors: [UIColor(red: 127.0/255.0, green: 127.0/255.0, blue: 127.0/255.0, alpha: 1.0).cgColor, UIColor(red: 47.0/255.0, green: 47.0/255.0, blue: 47.0/255.0, alpha: 1.0).cgColor], angle: 45)
if cellSelectionIndexPath == indexPath {
// it was already selected
cellSelectionIndexPath = nil
collectionView.deselectItem(at: indexPath, animated: true)
cell.cellView.addGradiant(colors: [UIColor.clear.cgColor, UIColor.clear.cgColor], angle: 0)
self.filtered = GlobalVariables.currentProduct.functions.filter { _ in
return true
}
self.functionsCollectionView.reloadData()
} else {
// wasn't yet selected, so let's remember it
cellSelectionIndexPath = indexPath
// Filter with seletec category name
let cellCategoryName = ICDatabase.objects(FunctionCategory.self)[indexPath.row]
self.filtered = GlobalVariables.currentProduct.functions.filter { function in
return function.functionCategory.contains(cellCategoryName)
}
self.functionsCollectionView.reloadData()
}
}
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
if collectionView == self.functionsCategoriesCollectionView {
if let cellToDeselect = collectionView.cellForItem(at: self.cellSelectionIndexPath) as? DevicePageFunctionsCategoriesCVCell {
cellToDeselect.isSelected = false
collectionView.deselectItem(at: self.cellSelectionIndexPath, animated: true)
cellToDeselect.cellView.addGradiant(colors: [UIColor.clear.cgColor, UIColor.clear.cgColor], angle: 0)
self.cellSelectionIndexPath = nil
// Get all functions
self.filtered = GlobalVariables.currentProduct.functions.filter { _ in
return true
}
self.functionsCollectionView.reloadData()
}
}
}
Thanks for your help!

Answer 1

Try this -
var selectedIndexPath: IndexPath?
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let cell = collectionView.cellForItem(at: indexPath)
cell.layer.backgroundColor = UIColor.black
self.selectedIndexPath = indexPath
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
let cell = collectionView.cellForItem(at: indexPath)
cell.layer.backgroundColor = UIColor.white
self.selectedIndexPath = nil
}

Answer 2

Collection cells reuse memory. So you have to manually manage data and UI. If your requirement is to select only one category cell in collection view at any time, keep one variable in collection view and update it in didSelect method.
var selectedIndexPath: IndexPath?
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
selectedIndexPath = indexPath
collectionView.reloadData()
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = UICollectionCell()
....
cell.backgroundColor = UIColor.black
if indexPath == selectedIndexPath {
cell.backgroundColor = UIColor.red
}
}