CustumCollectionView for Minzoo

CustomCollectionViewFlowLayout.swift

import UIKit

class CustomCollectionViewFlowLayout: UICollectionViewFlowLayout {
    
    private static let kMaxRow = 3
    var maxColumn = kMaxRow
    
    private var sectionCells = [[CGRect]]()
    private var contentSize = CGSize.zero
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override init() {
        super.init()
        
        self.sectionInset = UIEdgeInsets(top: 8, left: 8, bottom: 8, right: 8)
        self.minimumLineSpacing = 8
        self.minimumInteritemSpacing = 8
        self.sectionInset = UIEdgeInsetsMake(8, 8, 8, 8)
    }
    
    override func prepare() {
        super.prepare()
        sectionCells = [[CGRect]]()
        
        if let collectionView = self.collectionView {
            contentSize = CGSize(width: collectionView.bounds.width - collectionView.contentInset.left - collectionView.contentInset.right, height: 0)
            let smallCellSideLength: CGFloat = (contentSize.width - super.sectionInset.left - super.sectionInset.right - (super.minimumInteritemSpacing * (CGFloat(maxColumn) - 1.0))) / CGFloat(maxColumn)
            
            for section in (0..<collectionView.numberOfSections) {
                var cells = [CGRect]()
                let numberOfCellsInSection = collectionView.numberOfItems(inSection: section)
                var height = contentSize.height
                
                var x:CGFloat = 0
                var y:CGFloat = 0
                var cellwidth:CGFloat = 0
                var cellheight:CGFloat = 0
                
                for i in (0..<numberOfCellsInSection) {
                    let position = i  % (numberOfCellsInSection)
                    let cellPosition = position % 6
                    
                    switch cellPosition {
                    case 0:
                        if section % 2 == 0 {
                            x = super.sectionInset.left
                            y = contentSize.height + super.sectionInset.top
                            cellwidth = 2 * smallCellSideLength + super.minimumInteritemSpacing
                            cellheight = 2 * smallCellSideLength + super.minimumLineSpacing
                        }else{
                            x = super.sectionInset.left
                            y = contentSize.height + super.sectionInset.top
                            cellwidth = smallCellSideLength
                            cellheight = smallCellSideLength
                        }
                    case 1:
                        if section % 2 == 0 {
                            x = 2 * (smallCellSideLength + super.minimumInteritemSpacing) + super.sectionInset.left
                            y = 0 * (smallCellSideLength + super.minimumLineSpacing) + contentSize.height + super.sectionInset.top
                            cellwidth = smallCellSideLength; cellheight = smallCellSideLength
                        }else {
                            x = smallCellSideLength + super.minimumInteritemSpacing + super.sectionInset.left
                            y = (0 * (smallCellSideLength + super.minimumLineSpacing)) + contentSize.height + super.sectionInset.top
                            cellwidth = 2 * smallCellSideLength  + super.minimumInteritemSpacing
                            cellheight = 2 * smallCellSideLength + super.minimumLineSpacing
                        }
                    case 2:
                        if section % 2 == 0 {
                            x = 2 * (smallCellSideLength + super.minimumInteritemSpacing) + super.sectionInset.left
                            y = 1 * (smallCellSideLength + super.minimumLineSpacing) + contentSize.height + super.sectionInset.top
                            cellwidth = smallCellSideLength; cellheight = smallCellSideLength
                        }else{
                            x = super.sectionInset.left
                            y = (1 * (smallCellSideLength + super.minimumLineSpacing)) + contentSize.height + super.sectionInset.top
                            cellwidth = smallCellSideLength; cellheight = smallCellSideLength
                        }
                    case 3:
                        x = super.sectionInset.left
                        y = 2 * (smallCellSideLength + super.minimumLineSpacing) + contentSize.height + super.sectionInset.top
                        cellwidth = smallCellSideLength; cellheight = smallCellSideLength
                    case 4:
                        x = smallCellSideLength + super.minimumInteritemSpacing + super.sectionInset.left
                        y = 2 * (smallCellSideLength + super.minimumLineSpacing) + contentSize.height + super.sectionInset.top
                        cellwidth = smallCellSideLength; cellheight = smallCellSideLength
                    case 5:
                        x = 2 * (smallCellSideLength + super.minimumInteritemSpacing) + super.sectionInset.left
                        y = 2 * (smallCellSideLength + super.minimumLineSpacing) + contentSize.height + super.sectionInset.top
                        cellwidth = smallCellSideLength; cellheight = smallCellSideLength
                    default:
                        x = 0; y = 0
                        cellwidth = 0; cellheight = 0
                        break
                    }
                
                    let cellRect = CGRect(x: x, y: y, width: cellwidth, height: cellheight)
                    cells.append(cellRect)
                    
                    if (height < cellRect.origin.y + cellRect.height) {
                        height = cellRect.origin.y + cellRect.height
                    }
                }
                contentSize = CGSize(width: contentSize.width, height: height)
                sectionCells.append(cells)
            }
        }
    }
    
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        var layoutAttributes = [UICollectionViewLayoutAttributes]()
        
        if let collectionView = self.collectionView {
            for i in 0..<collectionView.numberOfSections {
                let numberOfCellsInSection = collectionView.numberOfItems(inSection: i);
                for j in 0..<numberOfCellsInSection {

                    let indexPath = IndexPath(row: j, section: i)
                    if let attributes = layoutAttributesForItem(at: indexPath) {
                        if (rect.intersects(attributes.frame)) {
                            layoutAttributes.append(attributes)
                        }
                    }
                }
            }
        }
        return layoutAttributes
    }
    
    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let attributes = super.layoutAttributesForItem(at: indexPath)
        attributes?.frame = sectionCells[indexPath.section][indexPath.row]
        return attributes
    }
    
    override var collectionViewContentSize : CGSize {
        return contentSize
    }
}

ViewController.swift

import UIKit

class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
    
    var myCollectionView : UICollectionView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let viewWidth = self.view.frame.width
        let viewHeight = self.view.frame.height
        let collectionFrame = CGRect(x: 0, y: 0, width: viewWidth, height: viewHeight)
        
        // CollectionViewのレイアウトを生成.
        let layout = CustomCollectionViewFlowLayout()

        // CollectionViewを生成.
        myCollectionView = UICollectionView(frame: collectionFrame, collectionViewLayout: layout)
        myCollectionView.backgroundColor = UIColor.white
        
        // Cellに使われるクラスを登録.
        myCollectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "MyCell")
        
        myCollectionView.delegate = self
        myCollectionView.dataSource = self
        
        self.view.addSubview(myCollectionView)
    }
    
    //Cellが選択された際に呼び出される
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        print("Section: \(indexPath.section)")
        print("Num: \(indexPath.row)")
        print("Number: \(indexPath.section * 6 + indexPath.row)")
    }
    
    //セクションあたりのセルの色を返す
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 6
    }
    //セクションの総数を返す
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 8
    }
    //Cellに値を設定する
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        
        let cell : UICollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "MyCell", for: indexPath as IndexPath)
        cell.backgroundColor = makeColor()
        let mainLabel = UILabel(frame: cell.frame)
        mainLabel.text = "\(indexPath.section)-\(indexPath.item)"
        mainLabel.textAlignment = .center
        mainLabel.backgroundColor = makeColor()
        cell.backgroundView = mainLabel
        cell.clipsToBounds = true
        cell.addSubview(mainLabel)
        return cell
    }
    //ランダムに色を生成する
    func makeColor() -> UIColor {
        let r: CGFloat = CGFloat(arc4random_uniform(255)+1) / 255.0
        let g: CGFloat = CGFloat(arc4random_uniform(255)+1) / 255.0
        let b: CGFloat = CGFloat(arc4random_uniform(255)+1) / 255.0
        let color: UIColor = UIColor(red: r, green: g, blue: b, alpha: 1.0)
        return color
    }
}