Swift 3 iOS dynamic layout CollectionView cell all in code

gistfile1.txt

 This is a collection view of vertically scrolling cells 1/3 high as wide and left hand image 1/3 width of screen with text label 2/3 screen width to the right of the image. This is completely created in code. I created a View Controller on the storyboard as I needed to attach a navgation controller. All you ever ever need to adjust is the imageAspectRatio and te image will always be 1/3 of the width of the cell row.

ViewController code.



import UIKit

let imageAspectRatio : CGFloat = 1.2

class MyViewController: UIViewController, 
                        UICollectionViewDelegateFlowLayout,
                        UICollectionViewDataSource {
    
    var collectionView: UICollectionView!
    
    var cellId = "Cell"
    
    var screenSize: CGRect!
    var screenWidth: CGFloat!
    var screenHeight: CGFloat!
    
    override func viewDidLoad() {

        super.viewDidLoad()
        
        screenSize = UIScreen.main.bounds
        screenWidth = screenSize.width
        screenHeight = screenSize.height

        let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
        layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        layout.itemSize = CGSize(width: screenWidth, height: (screenWidth / 3) * imageAspectRatio)
        layout.minimumInteritemSpacing = 0
        layout.minimumLineSpacing = 0
        layout.estimatedItemSize.height = (screenWidth / 3) * imageAspectRatio
        layout.estimatedItemSize.width = screenWidth
        
        collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
        
        collectionView.delegate = self
        
        collectionView.dataSource = self 

        collectionView!.register(WishListCell.self, forCellWithReuseIdentifier: "Cell")
        
        collectionView.backgroundColor = UIColor.white
        
        self.view.addSubview(collectionView)
        
    }

 }
    
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 20
    }
    
    func collectionView(_ collectionView: UICollectionView,
                        cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
 
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as? MyCell
        
        cell!.imageView.image = UIImage(named: "star")
        
        cell!.textLabel.text = "Text"
        
        return cell!
    }
}

CollectionViewCell code:


import UIKit

extension UIView {
    func addBorderTop(size: CGFloat, color: UIColor) {
        addBorderUtility(x: 0, y: 0, width: frame.width, height: size, color: color)
    }
    func addBorderBottom(size: CGFloat, color: UIColor) {
        addBorderUtility(x: 0, y: frame.height - size, width: frame.width, height: size, color: color)
    }
    func addBorderLeft(size: CGFloat, color: UIColor) {
        addBorderUtility(x: 0, y: 0, width: size, height: frame.height, color: color)
    }
    func addBorderRight(size: CGFloat, color: UIColor) {
        addBorderUtility(x: frame.width - size, y: 0, width: size, height: frame.height, color: color)
    }
    private func addBorderUtility(x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat, color: UIColor) {
        let border = CALayer()
        
        border.backgroundColor = color.cgColor
        
        border.frame = CGRect(x: x, y: y, width: width, height: height)
        
        layer.addSublayer(border)
    }
}

class MyCell: UICollectionViewCell {
    
    var textLabel: UILabel
    var imageView: UIImageView
    
    override init(frame: CGRect) {
        
        imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: frame.size.width / 3, height: (frame.size.width / 3) * imageAspectRatio))
        
        imageView.addBorderBottom(size: 1.0, color: .red)
        
        textLabel = UILabel(frame:  CGRect(x: 0, y: 0, width: frame.size.width/2*3 , height: (frame.size.width / 3) * imageAspectRatio)

        textLabel.addBorderBottom(size: 1.0, color: .red)

        super.init(frame: frame)
        
        imageView.contentMode = UIViewContentMode.scaleAspectFit
            
        contentView.addSubview(imageView)
        
        textLabel.font = UIFont.systemFont(ofSize: UIFont.smallSystemFontSize)
        
        textLabel.textAlignment = .center
        
        contentView.addSubview(textLabel)
        
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
}