How to have different cell size in flowlayout

Question

This is what I am able to make through a tutorial

This is the Screenshot of the app

But I have to make 1st and every 3rd Cell to be full width. How I supposed to do it?

The code is this

class MainViewController: UICollectionViewController
{

    // data source
    let publishers = Publishers()

    private let leftAndRightPaddings: CGFloat = 32.0
    private let numberOfItemsPerRow: CGFloat = 2.0
    private let heigthAdjustment: CGFloat = 100

    // MARK: - View controller life cycle

    override func viewDidLoad() {
        super.viewDidLoad()

        let width = (CGRectGetWidth(collectionView!.frame) - leftAndRightPaddings) / numberOfItemsPerRow
        let layout = collectionViewLayout as! UICollectionViewFlowLayout
        layout.itemSize = CGSizeMake(width, heigthAdjustment)
        print(width.description)

    }

    // MARK: - UICollectionViewDataSource

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

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

    private struct Storyboard
    {
        static let CellIdentifier = "PublisherCell"
    }

    override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell
    {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(Storyboard.CellIdentifier, forIndexPath: indexPath) as UICollectionViewCell

        return cell}

}

Answer 1

You need to implement this func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize method in your UICollectionViewDelegateFlowLayout