How to add uibutton action in a collection view cell?

Create the outlet of your UIButton in UICollectionViewCell, write In

func collectionView(_ collectionView: UICollectionView, 
                    cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    cell.button.tag = indexPath.row
    cell.button.addTarget(self, 
        action: #selector(self.yourFunc(), 
        for: .touchUpInside)
}

func yourFunc(sender : UIButton){
    print(sender.tag)
}

Make sure userInteraction is enable for the button as well as for UICollectionViewCell.

May be needful for you-

Write this code in cellForItemAtIndexPath

Swift 2.X

let editButton = UIButton(frame: CGRectMake(0, 20, 40,40))
editButton.setImage(UIImage(named: "editButton.png"), forState: UIControlState.Normal)
editButton.addTarget(self, action: #selector(editButtonTapped), forControlEvents: UIControlEvents.TouchUpInside)

cell.addSubview(editButton)

Swift 3.X

let editButton = UIButton(frame: CGRect(x:0, y:20, width:40,height:40))
editButton.setImage(UIImage(named: "editButton.png"), for: UIControlState.normal)
editButton.addTarget(self, action: #selector(editButtonTapped), for: UIControlEvents.touchUpInside)

cell.addSubview(editButton)

And perform your action-

override func viewDidLoad() {
       super.viewDidLoad()
}

@IBAction func editButtonTapped() -> Void {
    print("Hello Edit Button")
}