UILongPressureRecognizer with Image view - ios

Question

Good morning everyone,
I am a newbie Swift developer and I am facing the following problem implementing an exercise I am dealing with.
I have a collection view with collection cells displaying images I have imported in XCODE; when I tap with the finger on the screen I would like to replace the image currently being display with another one that i have also imported, and animate this replacement.
I am implementing the UITapLongPressureRecognizer method but i am getting confused on which state to implement for the recognizer, just to replace the first image view with the one I want to be shown when I tap the screen to scroll up-down.
As you can see from the code below the two recognizer I think should be more appropriate to be implemented are the "Begin" and "Ended".
My problem is that when the state .Begin starts I don't know how to animate the replacement of one image view with another and so when the state is .Ended I don't know how to replace the second image with the first one and animate the replacement (I want it to be like for example a Modal segue with "Cross Dissolve" transition).
Thank you in advance for your kindness and patience.
class MainViewController: UICollectionViewController {
var fashionArray = [Fashion]()
private var selectedIndexPath: NSIndexPath?
override func viewDidLoad() {
super.viewDidLoad()
selectedIndexPath = NSIndexPath()
//Register the cell
let collectionViewCellNIB = UINib(nibName: "CollectionViewCell", bundle: nil)
self.collectionView!.registerNib(collectionViewCellNIB, forCellWithReuseIdentifier: reuseIdentifier)
//Configure the size of the image according to the device size
let layout = collectionViewLayout as! UICollectionViewFlowLayout
let bounds = UIScreen.mainScreen().bounds
let width = bounds.size.width
let height = bounds.size.height
layout.itemSize = CGSize(width: width, height: height)
let longPressRecogn = UILongPressGestureRecognizer(target: self, action: "handleLongPress:")
collectionView!.addGestureRecognizer(longPressRecogn)
}
func handleLongPress(recognizer: UILongPressGestureRecognizer){
var cell: CollectionViewCell!
let location = recognizer.locationInView(collectionView)
let indexPath = collectionView!.indexPathForItemAtPoint(location)
if let indexPath = indexPath {
cell = collectionView!.cellForItemAtIndexPath(indexPath) as! CollectionViewCell
}
switch recognizer.state {
case .Began:
cell.screenTapped = false
case .Ended:
cell.screenTapped = false
default:
println("")
}
}

Answer 1

First of all, I suggest you to use UITapGestureRecognizer instead of long press. Because, as far as I understand, you only tap once instead of pressing for a time.
let tapRecognizer = UITapGestureRecognizer(target: self, action:Selector("tapped:"))
collectionView.addGestureRecognizer(tapRecognizer)
And when the user tapped, you can use UIView animations to change the image. You can check the Example II from the following link to get insight about animations.
http://www.appcoda.com/view-animation-in-swift/