CollectionViewCell press effect - ios

Question

I would like to give press effect for collectionViewCell on didSelectItem. On click I would like to add some color and after some delay I would like to revert the color. While trying the code below, press effect is added only after some delay. Can anyone suggest how to achieve this?
DispatchQueue.global(qos: .utility).async {
let cell = collectionView.cellForItem(at: indexPath) as ..cell
// Change bg color for foreground layer
DispatchQueue.main.async {
Timer.scheduledTimer(timeInterval: 0.10, target: self, selector: #selector(self.updateCell(timer:)) , userInfo: ["cell":cell,"collectionview":collectionView], repeats: false)
}
// Some calculations
}

Answer 1

.cellForItem(at: indexPath) as ..cell should usually be called in the main thread, you might see weird behavior if you are doing it from your utility queue
I suggest also to not use DispatchQueues and handle animation timing by yourself, there's already a nice function that does exactly what you want. This would be my suggestion:
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let cell = collectionView.cellForItem(at: indexPath) as ..cell
UIView.animate(withDuration: 0.2, delay: 0.4, options: .curveEaseInOut, animations: {
cell.backgroundColor = UIColor.red
}, completion: { _ in
// here the animation is done
})
}
Update with a nicer solution
Anyway, i think a nicer approach than handling the animation in the didSelectItemAt function of your UICollectionViewDelegate would be overriding the isSelected property of the cell.
In this example, I animate the backgroundColor whenever the selection state of the UICollectionViewCell changes - red when selected, green otherwise. Just replace that with whatever style you desire.
class YourCell: UICollectionViewCell {
override var isSelected: Bool {
willSet(newValue) {
let newColor = isSelected ? UIColor.red : UIColor.green
UIView.animate(withDuration: 1, delay: 0.4, options: .curveEaseInOut, animations: {
self.backgroundColor = newColor
}, completion: { _ in
// here the animation is done - nothing to do here probably
})
}
}
}