Code only example of https://github.com/ecerney/CollectionViewWaterfallLayout

WaterfallCollectionViewController.swift

import UIKit
import CollectionViewWaterfallLayout

class WaterfallCollectionViewController: UIViewController, UICollectionViewDataSource, CollectionViewWaterfallLayoutDelegate {

    var collectionView: UICollectionView!

    init () {
        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    lazy var cellSizes: [CGSize] = {
        var _cellSizes = [CGSize]()

        for _ in 0...100 {
            let random = Int(arc4random_uniform((UInt32(100))))

            _cellSizes.append(CGSize(width: 140, height: 50 + random))
        }

        return _cellSizes
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        let layout = CollectionViewWaterfallLayout()
        layout.sectionInset = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
        layout.headerInset = UIEdgeInsetsMake(20, 0, 0, 0)
        layout.headerHeight = 50
        layout.footerHeight = 20
        layout.minimumColumnSpacing = 10
        layout.minimumInteritemSpacing = 10
        self.collectionView = UICollectionView(frame: view.frame, collectionViewLayout: layout)
        view.addSubview(collectionView)

        self.collectionView.dataSource = self
        self.collectionView.delegate = self

        collectionView.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
        collectionView.registerClass(UICollectionReusableView.self, forSupplementaryViewOfKind: CollectionViewWaterfallElementKindSectionHeader, withReuseIdentifier: "Header")
        collectionView.registerClass(UICollectionReusableView.self, forSupplementaryViewOfKind: CollectionViewWaterfallElementKindSectionFooter, withReuseIdentifier: "Footer")
    }


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

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

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath)
        cell.backgroundColor = UIColor.whiteColor()
        if let label = cell.contentView.viewWithTag(1) as? UILabel {
            label.text = String(indexPath.row)
        }
        return cell
    }


    func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
        var reusableView: UICollectionReusableView? = nil

        if kind == CollectionViewWaterfallElementKindSectionHeader {
            reusableView = collectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: "Header", forIndexPath: indexPath)

            if let view = reusableView {
                view.backgroundColor = UIColor.redColor()
            }
        }
        else if kind == CollectionViewWaterfallElementKindSectionFooter {
            reusableView = collectionView.dequeueReusableSupplementaryViewOfKind(kind, withReuseIdentifier: "Footer", forIndexPath: indexPath)
            if let view = reusableView {
                view.backgroundColor = UIColor.blueColor()
            }
        }

        return reusableView!
    }

    // MARK: WaterfallLayoutDelegate

    func collectionView(collectionView: UICollectionView, layout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
        return cellSizes[indexPath.item]
    }
}