Why doesn't go CollectionViewCell? - ios

Question

I noticed that Topics CollectionViewCell was not gone when I debugged. Why is that?
the cells are all correct but the collectionview is not available.
The link of the project is below. you can also look from there.
here I define cell.
extension ArticlesVC: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return models.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: CollectionTableViewCell.identifier, for: indexPath) as! CollectionTableViewCell
cell.configure(with: models)
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 200
}
}
struct Model {
let text: String
let imageName: String
init(text: String, imageName: String) {
self.text = text
self.imageName = imageName
}
}
Here I define CollectionTableViewCell
class CollectionTableViewCell: UITableViewCell {
static let identifier = "CollectionTableViewCell"
var collectionView: UICollectionView?
var models = [Model]()
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
collectionView?.register(TopicsCollectionViewCell.self, forCellWithReuseIdentifier: TopicsCollectionViewCell.identifier)
collectionView?.delegate = self
collectionView?.dataSource = self
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
contentView.addSubview(collectionView!)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func layoutSubviews() {
super.layoutSubviews()
collectionView?.frame = contentView.bounds
}
func configure(with models: [Model]) {
self.models = models
collectionView?.reloadData()
}
}
extension CollectionTableViewCell: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return models.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: TopicsCollectionViewCell.identifier, for: indexPath) as! TopicsCollectionViewCell
cell.configure(with: models[indexPath.row])
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 250, height: 250)
}
}
**This TopicsCollectionViewCell **
class TopicsCollectionViewCell: UICollectionViewCell {
static let identifier = "TopicsCollectionViewCell"
let titleLabel: UILabel = {
let label = UILabel()
label.text = "label"
return label
}()
let photoImage: UIImageView = {
let imageView = UIImageView()
return imageView
}()
override init(frame: CGRect) {
super.init(frame: frame)
contentView.addSubview(titleLabel)
contentView.addSubview(photoImage)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func layoutSubviews() {
super.layoutSubviews()
photoImage.frame = CGRect(x: 3,
y: 3,
width: contentView.width - 6,
height: 150)
titleLabel.frame = CGRect(x: 3,
y: photoImage.bottom + 5,
width: contentView.width - 6,
height: contentView.height - photoImage.height - 6)
}
public func configure(with model: Model) {
print(model)
self.titleLabel.text = model.text
self.photoImage.image = UIImage(named: model.imageName)
}
}
This link is project with github

Answer 1

During execution those lines are useless as collectionView? is nil
collectionView?.register(TopicsCollectionViewCell.self, forCellWithReuseIdentifier: TopicsCollectionViewCell.identifier)
collectionView?.delegate = self
collectionView?.dataSource = self
You need to reorder the code by initing the collectionView first
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
contentView.addSubview(collectionView!)
collectionView?.register(TopicsCollectionViewCell.self, forCellWithReuseIdentifier: TopicsCollectionViewCell.identifier)
collectionView?.delegate = self
collectionView?.dataSource = self