Animate cell when pressed using Swift 3

If you need implement this functionality only for the specific cell, just add this code to you cell implementation:

override var isHighlighted: Bool {
  didSet {
    UIView.animate(withDuration: 0.5) {
      let scale: CGFloat = 0.9
      self.transform = self.isHighlighted ? CGAffineTransform(scaleX: scale, y: scale) : .identity
    }
  }
}

It is the same answer that suggested [pgdev][1] but for isHighlighted

Swift 4.2, inside the UICollectionViewCell

    //MARK:- Events
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesBegan(touches, with: event)
        animate(isHighlighted: true)
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesEnded(touches, with: event)
        animate(isHighlighted: false)
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesCancelled(touches, with: event)
        animate(isHighlighted: false)
    }

    //MARK:- Private functions
    private func animate(isHighlighted: Bool, completion: ((Bool) -> Void)?=nil) {
        let animationOptions: UIView.AnimationOptions = [.allowUserInteraction]
        if isHighlighted {
            UIView.animate(withDuration: 0.5,
                           delay: 0,
                           usingSpringWithDamping: 1,
                           initialSpringVelocity: 0,
                           options: animationOptions, animations: {
                            self.transform = .init(scaleX: 0.96, y: 0.96)
            }, completion: completion)
        } else {
            UIView.animate(withDuration: 0.5,
                           delay: 0,
                           usingSpringWithDamping: 1,
                           initialSpringVelocity: 0,
                           options: animationOptions, animations: {
                            self.transform = .identity
            }, completion: completion)
        }
    }

If you want to start animation when you touch on the cell, you can implement didHighlightItemAt. You probably want to reverse it in didUnhighlightItemAt:

override func collectionView(_ collectionView: UICollectionView, didHighlightItemAt indexPath: IndexPath) {
    UIView.animate(withDuration: 0.5) {
        if let cell = collectionView.cellForItem(at: indexPath) as? CustomCell {            
            cell.imageView.transform = .init(scaleX: 0.95, y: 0.95)
            cell.contentView.backgroundColor = UIColor(red: 0.95, green: 0.95, blue: 0.95, alpha: 1)
        }
    }
}

override func collectionView(_ collectionView: UICollectionView, didUnhighlightItemAt indexPath: IndexPath) {
    UIView.animate(withDuration: 0.5) {
        if let cell = collectionView.cellForItem(at: indexPath) as? CustomCell {
            cell.imageView.transform = .identity
            cell.contentView.backgroundColor = .clear
        }
    }
}

That yields: