UICollectionView knowledge supply and delegates programmatically

UICollectionViewCell programmatically

Should you’d like so as to add views to your cell, it’s best to use the init(body:) methodology, and arrange your view hierarchy there. As a substitute of awakeFromNib it’s best to type your views within the init methodology as nicely. You possibly can reset every little thing inside the same old prepareForReuse methodology. As you’ll be able to see by utilizing anchors typically it’s value to ditch IB fully. 🎉

class Cell: UICollectionViewCell {

    static var identifier: String = "Cell"

    weak var textLabel: UILabel!

    override init(body: CGRect) {
        tremendous.init(body: body)

        let textLabel = UILabel(body: .zero)
        textLabel.translatesAutoresizingMaskIntoConstraints = false
        contentView.addSubview(textLabel)
        NSLayoutConstraint.activate([
            contentView.centerXAnchor.constraint(equalTo: textLabel.centerXAnchor),
            contentView.centerYAnchor.constraint(equalTo: textLabel.centerYAnchor),
        ])
        self.textLabel = textLabel
        reset()
    }

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

    override func prepareForReuse() {
        tremendous.prepareForReuse()
        
        reset()
    }

    func reset() {
        textLabel.textAlignment = .middle
    }
}

UICollectionView programmatically

Creating assortment view controllers utilizing solely Swift code requires only some further traces. You possibly can implement loadView and create your UICollectionView object there. Retailer a weak reference of it contained in the controller, and the remaining is similar.

class ViewController: UIViewController {

    weak var collectionView: UICollectionView!

    var knowledge: [Int] = Array(0..<10)

    override func loadView() {
        tremendous.loadView()

        let collectionView = UICollectionView(
            body: .zero, 
            collectionViewLayout: UICollectionViewFlowLayout()
        )
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(collectionView)
        NSLayoutConstraint.activate([
            view.topAnchor.constraint(equalTo: collectionView.topAnchor),
            view.bottomAnchor.constraint(equalTo: collectionView.bottomAnchor),
            view.leadingAnchor.constraint(equalTo: collectionView.leadingAnchor),
            view.trailingAnchor.constraint(equalTo: collectionView.trailingAnchor),
        ])
        collectionView = collectionView
    }

    override func viewDidLoad() {
        tremendous.viewDidLoad()

        collectionView.dataSource = self
        collectionView.delegate = self
        collectionView.register(Cell.self, forCellWithReuseIdentifier: Cell.identifier)
        collectionView.alwaysBounceVertical = true
        collectionView.backgroundColor = .white
    }
}

extension ViewController: UICollectionViewDataSource {

    func collectionView(
        _ collectionView: UICollectionView,
        numberOfItemsInSection part: Int
    ) -> Int {
        knowledge.depend
    }

    func collectionView(
        _ collectionView: UICollectionView,
        cellForItemAt indexPath: IndexPath
    ) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(
            withReuseIdentifier: Cell.identifier, 
            for: indexPath
        ) as! Cell

        let knowledge = knowledge[indexPath.item]
        cell.textLabel.textual content = String(knowledge)
        return cell
    }
}

extension ViewController: UICollectionViewDelegate {

    func collectionView(
        _ collectionView: UICollectionView, 
        didSelectItemAt indexPath: IndexPath
    ) {

    }
}

extension ViewController: UICollectionViewDelegateFlowLayout {

    func collectionView(
        _ collectionView: UICollectionView,
        structure collectionViewLayout: UICollectionViewLayout,
        sizeForItemAt indexPath: IndexPath
    ) -> CGSize {
        .init(width: collectionView.bounds.width, peak: 44)
    }

    func collectionView(
        _ collectionView: UICollectionView,
        structure collectionViewLayout: UICollectionViewLayout,
        insetForSectionAt part: Int
    ) -> UIEdgeInsets {
        .init(high: 0, left: 0, backside: 0, proper: 0) //.zero
    }

    func collectionView(
        _ collectionView: UICollectionView,
        structure collectionViewLayout: UICollectionViewLayout,
        minimumInteritemSpacingForSectionAt part: Int
    ) -> CGFloat {
        0
    }

    func collectionView(
        _ collectionView: UICollectionView,
        structure collectionViewLayout: UICollectionViewLayout,
        minimumLineSpacingForSectionAt part: Int
    ) -> CGFloat {
        0
    }
}

That was simple. Anchors are actually highly effective, Interface Builder is extraordinarily useful, however typically it’s simply sooner to create your views from code. The selection is yours, however please don’t be afraid of coding person interfaces! 😅