View with continuous scroll; both horizontal and vertical

Question

I have been struggling with this assignment for quite some time now. What I would like to develop is a scrollview or collectionview which scrolls continuously both vertical

Answer 1

@updated for swift 3 and changed how the maxRow is calculated otherwise the last column is cutoff and can cause errors

import UIKit

class NodeMap : UICollectionViewController {
    var rows = 10
    var cols = 10

    override func viewDidLoad(){
        self.collectionView!.collectionViewLayout = NodeLayout(itemWidth: 400.0, itemHeight: 300.0, space: 5.0)
    }

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return rows
    }

    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return cols
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        return collectionView.dequeueReusableCell(withReuseIdentifier: "node", for: indexPath)
    }
}

class NodeLayout : UICollectionViewFlowLayout {
    var itemWidth : CGFloat
    var itemHeight : CGFloat
    var space : CGFloat
    var columns: Int{
        return self.collectionView!.numberOfItems(inSection: 0)
    }
    var rows: Int{
        return self.collectionView!.numberOfSections
    }

    init(itemWidth: CGFloat, itemHeight: CGFloat, space: CGFloat) {
        self.itemWidth = itemWidth
        self.itemHeight = itemHeight
        self.space = space
        super.init()
    }

    required init(coder aDecoder: NSCoder) {
        self.itemWidth = 50
        self.itemHeight = 50
        self.space = 3
        super.init()
    }

    override var collectionViewContentSize: CGSize{
        let w : CGFloat = CGFloat(columns) * (itemWidth + space)
        let h : CGFloat = CGFloat(rows) * (itemHeight + space)
        return CGSize(width: w, height: h)
    }

    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
        let x : CGFloat = CGFloat(indexPath.row) * (itemWidth + space)
        let y : CGFloat = CGFloat(indexPath.section) + CGFloat(indexPath.section) * (itemHeight + space)
        attributes.frame = CGRect(x: x, y: y, width: itemWidth, height: itemHeight)
        return attributes
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        let minRow : Int = (rect.origin.x > 0) ? Int(floor(rect.origin.x/(itemWidth + space))) : 0
        let maxRow : Int = min(columns - 1, Int(ceil(rect.size.width / (itemWidth + space)) + CGFloat(minRow)))
        var attributes : Array = [UICollectionViewLayoutAttributes]()
        for i in 0 ..< rows {
            for j in minRow ... maxRow {
                attributes.append(self.layoutAttributesForItem(at: IndexPath(item: j, section: i))!)
            }
        }
        return attributes
    }
}