· 1 min learn
On this fast UIKit tutorial I am going to present you learn how to create a easy UICollectionView with out Interface Builder, however solely utilizing Swift.
UICollectionViewCell programmatically
For those who’d like so as to add views to your cell, it’s best to use the init(body:) technique, and arrange your view hierarchy there. As an alternative of awakeFromNib it’s best to type your views within the init technique as properly. You’ll be able to reset all the things inside the standard prepareForReuse technique. As you may see by utilizing anchors generally it’s price 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 carried out")
}
override func prepareForReuse() {
tremendous.prepareForReuse()
reset()
}
func reset() {
textLabel.textAlignment = .heart
}
}
UICollectionView programmatically
Creating assortment view controllers utilizing solely Swift code requires just a few extra strains. You’ll be able to implement loadView and create your UICollectionView object there. Retailer a weak reference of it contained in the controller, and the remaining is identical.
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(prime: 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 straightforward. Anchors are actually highly effective, Interface Builder is extraordinarily useful, however generally it’s simply quicker to create your views from code. The selection is yours, however please don’t be afraid of coding consumer interfaces! 😅
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