Accessing indexPath in a collectionview - ios

Question

I have a collectionview cell which has an image on it and a button below it. Now when I click on this button, I want to load a tableviewCell which has on it the image from the collectionview. To achieve this, I did this initially..
func SellBtnTapped(_ sender: UIButton) {
let indexPath = collectionView?.indexPath(for: ((sender.superview?.superview) as! RecipeCollectionViewCell))
self.photoThumbnail.image = self.arrayOfURLImages[(indexPath?.row)!]
and photoThumbnail is defined like so...var photoThumbnail: UIImageView! But doing this gives a crash telling 'Unexpectedly found nil while unwrapping an optional value' So I tried this..
let point = sender.convert(CGPoint.zero, to: self.collectionView)
let myIndexPath = self.collectionView.indexPathForItem(at: point)
self.photoThumbnail.image = self.arrayOfURLImages[(myIndexPath?.row)!]
But again, the same crash of Unexpectedly found nil.... is happening. Any idea as to what could be the issue..?
EDIT:
This is the code for cellForItemAtIndex...
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: identifier, for: indexPath as IndexPath) as! RecipeCollectionViewCell
cell.sellButton.tag = indexPath.item
cell.sellButton.addTarget(self,action: #selector(SellBtnTapped(_:)),for: .touchUpInside)
return cell
}

Answer 1

It's because you alway get nil your indexPath.
Another approach is
in collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath method
set tag of your cell's button like
cell.myButton.tag = indexPath.item
And in SellBtnTapped method use below code for get indexPath
let indexPath = NSIndexPath(item: sender.tag, section: 0) // set section as you want
let cell = collectionView.cellForItem(at: indexPath as NSIndexPath) as! RecipeCollectionViewCell
Now by use of cell you can get image object that is on it or use self.arrayOfURLImages to get right image. and do your further stuff.

Answer 2

I prefer avoiding tags altogether. I wrote this a while ago and still find it useful.
extension UIView {
var superCollectionViewCell: UICollectionViewCell? {
if let cell = self as? UICollectionViewCell {
return cell
} else {
return superview?.superCollectionViewCell
}
}
var superCollectionView: UICollectionView? {
if let collectionView = self as? UICollectionView {
return collectionView
} else {
return superview?.superCollectionView
}
}
var indexPathOfSuperCollectionViewCell: IndexPath? {
guard let cell = superCollectionViewCell, let collectionView = superCollectionView else { return nil }
return collectionView.indexPath(for: cell)
}
}
This turns your action into
func SellBtnTapped(_ sender: UIButton) {
guard let indexPath = sender.indexPathOfSuperCollectionViewCell else {
print("button has no index path")
return
}
self.photoThumbnail.image = self.arrayOfURLImages[indexPath.row]
}