UICollectionView 只显示最后一个单元格

Question

I'm doing a collectionView programmatically for a menu. So basic I press a button and the menu appears from the bottom of my screen. That's is working, the problem is, that I'm trying to set label on my collectionview. I set everything, but when I run the app, just my last cell show up. So here is my CollectionView:

class SettingsLauncher: NSObject, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate, UICollectionViewDataSource {


    private var blackView = UIView()

    let collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
        cv.backgroundColor = .white
        return cv
    }()
   override init() {
        super.init()
        collectionView.delegate = self
        collectionView.dataSource = self
        collectionView.register(MenuCell.self, forCellWithReuseIdentifier: K.CollectioViewCell.cell_identifier_menu)
    }

    //MARK: - Collection View DataSource

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        3
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: K.CollectioViewCell.cell_identifier_menu, for: indexPath)
        return cell
    }    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: collectionView.frame.width, height: 60)
    }
}

And here is my cell configuration:

class BaseCell: UICollectionViewCell {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }

    func setupView() {

    }

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


let nameLabel: UILabel = {
    let label = UILabel()
    label.text = "Test"
    label.backgroundColor = .red
    return label
}()

let labelArray = ["nameLabel" : nameLabel]

class MenuCell: BaseCell {


    override func setupView() {
        super.setupView()
        backgroundColor = .blue
        addSubview(nameLabel)
        let horizontalConstraint = NSLayoutConstraint.constraints(withVisualFormat: "H:|-[nameLabel]-|", options: [], metrics: nil, views: labelArray)
        let verticalConstraint = NSLayoutConstraint.constraints(withVisualFormat: "V:|[nameLabel]|", options: [], metrics: nil, views: labelArray)

        nameLabel.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate(horizontalConstraint)
        NSLayoutConstraint.activate(verticalConstraint)


    }
}

Answer 1

Views can only have one superview. Your nameLabel is created once, then added to each MenuCell, which means your label is removed from the previous cells. Create a UILabel for each cell and your code should work fine, like so:

class MenuCell: BaseCell {

   let nameLabel: UILabel = {
       let label = UILabel()
       label.text = "Test"
       label.backgroundColor = .red
       return label
   }()

    override func setupView() {
        super.setupView()
        backgroundColor = .blue
        addSubview(nameLabel)
        let horizontalConstraint = NSLayoutConstraint.constraints(withVisualFormat: "H:|-[nameLabel]-|", options: [], metrics: nil, views: labelArray)
        let verticalConstraint = NSLayoutConstraint.constraints(withVisualFormat: "V:|[nameLabel]|", options: [], metrics: nil, views: labelArray)

        nameLabel.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate(horizontalConstraint)
        NSLayoutConstraint.activate(verticalConstraint)


    }
}