Basic List - UICollectionView. Two labels

CollectionView.swift

//
//  ListViewController.swift
//
//  Created by Paul McKellar on 11/1/16.
//  Copyright © 2016 Paul McKellar. All rights reserved.
//

import Foundation
import UIKit

class BlogViewCell: UICollectionViewCell {
    
    var titleLabel: UILabel!
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        self.titleLabel = UILabel()
        self.titleLabel.frame = CGRect(x: 0, y: 0, width: self.frame.width, height: self.frame.height)
        self.titleLabel.tintColor = UIColor.black
        self.addSubview(titleLabel)

        return;
    }
    
    required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented"); }
    
}

class ListLayoutAttributes: UICollectionViewLayoutAttributes {
    var height: CGFloat = 0.0
}

class ListOffsetLayout: UICollectionViewLayout {
    
    var delegate: BlogsListViewController!

    private var items = [ListLayoutAttributes]()
    
    private var contentHeight:CGFloat = 0.0
    private var contentWidth: CGFloat {
        let insets = collectionView!.contentInset
        return collectionView!.bounds.width - (insets.left + insets.right)
    }
    
    override class var layoutAttributesClass: AnyClass {
        return ListLayoutAttributes.self
    }
    
    override func prepare() {
        for itemNumber in 0 ..< collectionView!.numberOfItems(inSection: 0) {
            
            let indexPath = IndexPath(row: itemNumber, section: 0)
            
            let height = delegate.heightForCell(indexPath)
            
            let attributes = ListLayoutAttributes(forCellWith: indexPath as IndexPath)
            attributes.height = height
            
            let frame = CGRect(x: 0, y: height * CGFloat(itemNumber), width: contentWidth, height: height)
            attributes.frame = frame
            
            items.append(attributes)
            
            contentHeight = contentHeight + height
        }
    }
    
    override var collectionViewContentSize: CGSize {
        return CGSize(width: contentWidth, height: contentHeight)
    }
    
    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        return items[indexPath.row]
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        var layoutAttributes = [ListLayoutAttributes]()
        
        for attributes in items {
            if attributes.frame.intersects(rect) {
                layoutAttributes.append(attributes)
            }
        }
        return layoutAttributes
    }
    
}

class BlogsListViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
    
    var layout: ListOffsetLayout!
    var collectionView: UICollectionView!
    
    var blogList = ["nevver", "socmoth"]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.layout = ListOffsetLayout()
        self.layout.delegate = self

        let historyFrame = CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height)
        self.collectionView = UICollectionView(frame: historyFrame, collectionViewLayout: layout)
        self.collectionView.delegate   = self
        self.collectionView.dataSource = self

        self.view.backgroundColor = UIColor.white
        self.collectionView.backgroundColor = UIColor.clear

        self.collectionView.register(BlogViewCell.self, forCellWithReuseIdentifier: "blogViewCell")
        self.view.addSubview(self.collectionView)
    }
    
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.blogList.count
    }
        
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = self.collectionView.dequeueReusableCell(withReuseIdentifier: "blogViewCell", for: indexPath as IndexPath) as! BlogViewCell
        
        cell.titleLabel.text = self.blogList[indexPath.row]
        
        return cell
    }
    
    func heightForCell(_ indexPath: IndexPath) -> CGFloat {
        return CGFloat(44.0)
    }
    
}