UICollectionViewCell change in one seen in multiple cells in collectionview - ios

Question

I have a uicollectionview with collectionviewcells and each cell has a boolean value associated with a favorites button. There are over 50 cells positioned vertically (four cells are viewable at a time). If the favorite button is clicked it toggles between a highlighted image and a non-highlighted image.
That functionality works, but for some reason when I click one then scroll down I see other cells with their favorite button highlighted. When I scroll back up the cell favorite button is no longer highlighted.
Is there something missing from this code?
NOTE:: As a default I set each cell's boolean value to false. It's only changed when I click on the cell's favorite button.
My code below:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! SimpleDispensarySubCell
cell.backgroundColor = UIColor.init(white: 0.10, alpha: 0.25)
cell.infoLine2TextVw.text = ""
cell.infoLine3TextVw.text = ""
if let heading_name = self.dict_dict_holder[indexPath.item]["Name"]{
cell.headerTextVw.text = heading_name
cell.infoLine1TextVw.text = self.dict_dict_holder[indexPath.item]["Phone"]
}
if cell.isFavorite{
cell.isFavorite = true
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_fill_icon"), for: .normal)
}
else{
cell.isFavorite = false
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_nofill_icon"), for: .normal)
}
cell.bringSubview(toFront: cell.headerTextVw)
//cell.favorite_button.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(AddFavorite(withSender:))))
cell.favorite_button.addTarget(self, action:#selector(AddFavorite), for: .touchUpInside)
return cell
}
#objc func AddFavorite(withSender sender:UIButton){
let cell = sender.superview as! SimpleDispensarySubCell
if cell.isFavorite{
cell.isFavorite = false
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_nofill_icon"), for: .normal)
}
else{
cell.isFavorite = true
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_fill_icon"), for: .normal)
}
}

Answer 1

It's because you are using collectionView.dequeueReusableCell you should define an array to hold favorite state of each cell on it. It could solve your problem.
let favoriteStateArray = countOfRows;
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! SimpleDispensarySubCell
cell.backgroundColor = UIColor.init(white: 0.10, alpha: 0.25)
cell.infoLine2TextVw.text = ""
cell.infoLine3TextVw.text = ""
if let heading_name = self.dict_dict_holder[indexPath.item]["Name"]{
cell.headerTextVw.text = heading_name
cell.infoLine1TextVw.text = self.dict_dict_holder[indexPath.item]["Phone"]
}
if favoriteStateArray[indexPath.row]{
cell.isFavorite = true
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_fill_icon"), for: .normal)
}
else{
cell.isFavorite = false
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_nofill_icon"), for: .normal)
}
cell.bringSubview(toFront: cell.headerTextVw)
//cell.favorite_button.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(AddFavorite(withSender:))))
cell.favorite_button.addTarget(self, action:#selector(AddFavorite), for: .touchUpInside)
return cell
}
#objc func AddFavorite(withSender sender:UIButton){
let cell = sender.superview as! SimpleDispensarySubCell
let index = collectionView.indexPath(for: cell)
if favoriteStateArray[indexPath.row]{
favoriteStateArray[indexPath.row] = false
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_nofill_icon"), for: .normal)
}
else{
favoriteStateArray[indexPath.row] = false
cell.favorite_button.setImage(#imageLiteral(resourceName: "heart_fill_icon"), for: .normal)
}
}

Answer 2

Since the cells are getting reused changes are affecting multiple cells.
You can use prepare for reuse method to clear changes that must affect only a particular cell and Clear the cell and prepare it for Reuse.
override func prepareForReuse() {
cell.isFavorite = false
super.prepareForReuse()
}