How to exchange place of UIcollectionView cells with animation ?

Question

I have a UIcollection view where i have 2 different sized cell. The last cell is always bigger and exposed and all the other are small and half hidden.

Now when the user taps the half hidden cells i want to pick those cell and replace their position with the cell in the front (exposed) with an animation.

Until now i am reshuffling the data in the data source and reloading it which serves the purpose but no animation so far as couldn't find anything useful.

Any help will be appreciated. Note: I am using Swift.

Thanks,

Answer 1

Try this:

import UIKit

private let reuseIdentifierBig = "bigger"
private let reuseIdentifierSmall = "small"

class CollectionViewController: UICollectionViewController {

let array = [0,1,2,3,4]
var selectedIndex:NSIndexPath?
var preSelectedIndex:NSIndexPath?

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

override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return 1
}


override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return array.count
}

override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    if selectedIndex != indexPath {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifierSmall, forIndexPath: indexPath)
        return cell
    } else {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifierBig, forIndexPath: indexPath)
        return cell
    }
}

override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    preSelectedIndex = selectedIndex
    selectedIndex = indexPath
    collectionView.reloadItemsAtIndexPaths([indexPath])
    if preSelectedIndex != nil {
        collectionView.reloadItemsAtIndexPaths([preSelectedIndex!])
    }
}

}