WaterfallLayout | water-fall layout in iOS | iOS library

     //: Playground - noun: a place where people can play

import UIKit

class Controller: UIViewController, UICollectionViewDelegateFlowLayout, WaterfallLayoutDelegate {

    let collectionView = UICollectionView(frame: CGRect.zero)
    let waterfallCollectionView = UICollectionView(frame: CGRect.zero)

    override func viewDidLoad() {

        collectionView.delegate = self
        collectionView.collectionViewLayout = UICollectionViewFlowLayout()

        waterfallCollectionView.delegate = self
        let waterfallLayout = WaterfallLayout()
        waterfallLayout.delegate = self
        waterfallCollectionView.collectionViewLayout = waterfallLayout
    }

    //MARK: - WaterfallLayoutDelegate

    func collectionView(_ collectionView: UICollectionView, layout: WaterfallLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

        return CGSize.zero
    }

    //MARK: - UICollectionViewDelegateFlowLayout

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

        return CGSize.zero
    }
}

//MARK: - Just for test

protocol WaterfallLayoutDelegate: class {

    func collectionView(_ collectionView: UICollectionView, layout: WaterfallLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
}

class WaterfallLayout: UICollectionViewLayout {

    weak var delegate: WaterfallLayoutDelegate?
}