SliddingIssue

First Commit

I have a UICollectionview which has several custom cells. One of the cells (C1) is used as a 'Menu - with a UICollectionview inside' and hook to its class C1.swift (Subclass of UICollectionCell), another cell(C2) is used to display items. C2 has also a UICollectionview with its own custom cells and hook to C2.swift (Subclass of UICollectionCell).

I created an horizontalBarView to show which cell in C1 was selected:

Inside C1.swift, I have the following code:

@IBOutlet weak var listingMenuCV: UICollectionView!

var profileItemCell: ProfileItemsCell?
  ....
 override func awakeFromNib() {
 super.awakeFromNib()
 setupViews()
 }

 override func setupViews() {

   self.listingMenuCV?.register(UINib(nibName: "C1MenuCell", bundle: nil), forCellWithReuseIdentifier: menuCellID)

  self.layout?.itemSize = CGSize(width: self.frame.width / 3, height: self.frame.height - 5)

  self.layout?.minimumLineSpacing = 0

  setupHorizontalBar()

  }

//Mark: setup the horizontal bar view to know which cell was selected

func setupHorizontalBar() {
    let horizontalBarView = UIView()
    horizontalBarView.backgroundColor = UIColor.rgb(255, green: 0, blue: 128)
    horizontalBarView.translatesAutoresizingMaskIntoConstraints = false
    addSubview(horizontalBarView)

    horizontalBarLeftAnchorConstraint = horizontalBarView.leftAnchor.constraint(equalTo: self.leftAnchor)
    horizontalBarLeftAnchorConstraint?.isActive = true
    horizontalBarLeftAnchorConstraint?.identifier = "HorizontalBarConstraint"

    horizontalBarView.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
    horizontalBarView.widthAnchor.constraint(equalTo: self.widthAnchor, multiplier: 1/3).isActive = true
    horizontalBarView.heightAnchor.constraint(equalToConstant: 2).isActive = true


   }

And inside collection- didSelectItem function I have the following code - to slide the horizontalbarView:

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

   let x = CGFloat(indexPath.item) * frame.width / 3
   horizontalBarLeftAnchorConstraint?.constant = x

    UIView.animate(withDuration: 0.75, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
      self.layoutIfNeeded()
    }, completion: nil)


  }

Everything works fine. However, I want to make the horizontalBar to slide to the correct cell inside C1 from C2.swift

So in C2.swift I have the following code:

  @IBOutlet weak var profileItemsCV: UICollectionView!

//Mark: Var to access the other variable from the ListingMenu Cell lazy var listingBar: C1MenuCell = { let lm = C1MenuCell() lm.profileItemCell = self return lm }()

//: Mark - Scrolling to make the horizontalBar to slide

     func scrollViewDidScroll(_ scrollView: UIScrollView) {
       let xScrollValue = scrollView.contentOffset.x
       listingBar.horizontalBarLeftAnchorConstraint?.constant = xScrollValue / 3
      }

Unfortunately, that doesn't seems to work, as it looks like that listingMenuCV.delegate is nil, each time I start to scroll profileItemsCV in C2 cell.