How to update a label text with button inside a collection view in swift 4

Question

I have a collection view inside a table view. There are two plus minus buttons in collection view cell. Now i have to update a label on the plus minus buttons action which is outside of table view. Thanks in advance.

I have to update a Slot: (label) by clicking on plus minus button.

I tried something like this with the delegate protocol.

I declare a delegate in my collection view class.

 protocol SlotsCollectionViewCellDelegate: NSObjectProtocol {
func didTapOnIncrement(Int: Int)
func didTapOnDecrement(Int: Int)

}

//after that,

 var delegate: SlotsCollectionViewCellDelegate?


 @IBAction func plusBtnAction(_ sender: Any) {
     self.delegate?.didTapOnIncrement(Int: cartCount)
  }

   @IBAction func minusBtnAction(_ sender: Any) {
     delegate?.didTapOnDecrement(cell: self)
   }

And in my Main View Controller

extension MainViewController: SlotsCollectionViewCellDelegate {

func didTapOnIncrement(Int: Int) {
       cartSlot_lbl.text = Int.description
     }

     func didTapOnDecrement(Int: Int) {
         cartSlot_lbl.text = Int.description
     }

}

Answer 1

If I understood correctly, each time you push + or - you want to update slot label. In my opinion the easiest and fastest way to achieve this it's using NotificationCenter.default.post

In your collection view cell on button action write:

NotificationCenter.default.post(name: Notification.Name("postAction"), object: numberToIncreaseOrDecrease)

In your MainViewController where you have the slot label, add this code in view did load:

NotificationCenter.default.addObserver(self, selector: #selector(updateSlotValue(_:)), name: NSNotification.Name("postAction"), object: nil)

And out from the view did load add this function:

 @objc func updateSlotValue(_ notification: Notification) {
    let value = notification.object as! Int
    cartSlot_lbl.text.text = value
}