Swift CollectionView Deselection not working - ios

Question

I am using a custom UICollectionViewFlowLayout class to achieve multi-scroll behaviour of scroll view. No problem in that.
But to make custom selection and deselection, I need to use custom code inside shouldSelectItemAt function for proper selection/deselection.
Here is the code for it:
Inside MyCustomCollectionViewController:
func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
if(collectionView == customContentCollectionView){
let cell:MyContentCell = collectionView.cellForItem(at: indexPath)! as! MyCollectionViewController.MyContentCell
if(self.bubbleArray[indexPath.section][indexPath.item].umid != ""){
// DESELECTION LOGIC
if(previouslySelectedIndex != nil){
let (bubbleBorder, bubbleFill) = getBubbleColor(selected: false)
// following line is error prone (executes but may or may not fetch the cell, sometimes deselect sometimes doesn't)
let prevCell = try collectionView.cellForItem(at: previouslySelectedIndex) as? MyCollectionViewController.MyContentCell
prevCell?.shapeLayer.strokeColor = bubbleBorder.cgColor
prevCell?.shapeLayer.fillColor = bubbleFill.cgColor
prevCell?.shapeLayer.shadowOpacity = 0.0
prevCell?.labelCount.textColor = bubbleBorder
}
previouslySelectedIndex = []
previouslySelectedIndex = indexPath
// SELECTION LOGIC
if(self.bubbleArray[indexPath.section][indexPath.item].interactions != ""){
let (bubbleBorder, bubbleFill) = getBubbleColor(selected: true)
cell.shapeLayer.strokeColor = bubbleBorder.cgColor
cell.shapeLayer.fillColor = bubbleFill.cgColor
cell.shapeLayer.shadowOffset = CGSize(width: 0, height: 2)
cell.shapeLayer.shadowOpacity = 8
cell.shapeLayer.shadowRadius = 2.0
cell.labelCount.textColor = UIColor.white
}
}
return false
}
return true
}
The code for MyContentCell:
class MyContentCell: UICollectionViewCell{ // CODE TO CREATE CUSTOM CELLS
var gradient = CAGradientLayer()
var shapeLayer = CAShapeLayer()
var horizontalLine = UIView()
var verticalLeftLine = UIView()
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)!
setup()
}
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
let labelCount: UILabel = {
let myLabel = UILabel()
return myLabel
}()
func setup(){ // initializing cell components here as well as later in cellForItemAt method
............
}
override func prepareForReuse() {
self.shapeLayer.fillColor = UIColor.white.cgColor
self.shapeLayer.shadowOpacity = 0.0
}
}
May be the problem is, when a cell is selected and just dragged out of screen, its perhaps might not being destroyed, that's why the prepare for reuse function is not tracking it to make the deselection. So kindly tell me how to deselect a cell which is just gone outside the screen (visible index)?

Answer 1

You need to invalidate layout
collectionView?.collectionViewLayout.invalidateLayout()