Animate cell when pressed using Swift 3

Question

My problem is really simple. I would like to animate a cell within a collectionView. Indeed, I would like to show a grey background behind the cell and scale down the image inside.

It would be (almost) the same effect than Pinterest:

I used to code that animation on buttons, but I never did that on a cell. How can link a cell to a touchUpInside or TouchDown action for example ?

Answer 1

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: