Reload collection view data from another view class

Question

I have two containers in a view. The top one has a collection view. I want to update my collection view from a button when a button is hit from the below container. My button is also changing the value of an array, which my collection view uses.

I thought didSet would do the job but unfortunately did not work.

Top:

class TopViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

    @IBOutlet weak var favoritesCV: UICollectionView!

    var myFavorites = [] {
        didSet {
            self.favoritesCV.reloadData()
        }
    }


    override func viewDidAppear(animated: Bool) {
        myFavorites = favoritesInstance.favoritesArray
    }

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

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

        let cell : FavoritesCollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! FavoritesCollectionViewCell

        var myPath = myFavorites[indexPath.row] as! String
        cell.myImage.image = UIImage(named: myPath)
        return cell
    }
 }

Bottom:

class BottomViewController: UIViewController, UIScrollViewDelegate  {

    @IBAction func addFavorites(sender: AnyObject) {
         favoritesInstance.favoritesArray.append("aaaa.jpg")
    }
}

Storage Class:

class Favorites {
    var favoritesArray:Array <AnyObject>

    init(favoritesArray:Array <AnyObject>) {
        self.favoritesArray = favoritesArray
    }
}

var favoritesInstance = Favorites(favoritesArray:[])

Answer 1

I have added

NSNotificationCenter.defaultCenter().addObserver(self, selector: "loadList:", name:"load", object: nil)

in my viewdidload of my collection view class. also added a selector which reloads my data when it is called by the Notification Center

func loadList(notification: NSNotification){
    self.favoritesCV.reloadData()
}

and for the other class where the button is pressed:

NSNotificationCenter.defaultCenter().postNotificationName("load", object: nil)

Swift 3:

NotificationCenter.default.addObserver(self, selector: #selector(loadList), name:NSNotification.Name(rawValue: "load"), object: nil)

NotificationCenter.default.post(name: NSNotification.Name(rawValue: "load"), object: nil)

Answer 2

Swift 4:

1st class:

NotificationCenter.default.post(name: NSNotification.Name("load"), object: nil)

Class with collectionView:

in viewDidLoad():

NotificationCenter.default.addObserver(self, selector: #selector(loadList(notification:)), name: NSNotification.Name(rawValue: "load"), object: nil)

and function:

@objc func loadList(notification: NSNotification) {
  self.collectionView.reloadData()
}