swift - 嵌套 UICollectionView 重复单元格

Question

我有一段时间遇到一个问题，但还没有解决。最后，我想就以下问题寻求您的帮助。

我在我的项目中实现了一个嵌套的UICollectionView，并且在主 Collection View 上向下滚动时出现重复的单元格。

我不知道如何解决这个问题。

MainPageViewController.swift

import UIKit

class MainPageViewController: UIViewController, UICollectionViewDataSource,  UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {

override func viewDidLoad() {
    super.viewDidLoad()

    print("icinde")

    let navBar = UINavigationBar()
    let navItem = UINavigationItem(title: "Promotions")
    navBar.setItems([navItem], animated: false)
    self.view.addSubview(navBar)

    let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
    layout.scrollDirection = .vertical
    var collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
    collectionView.dataSource = self
    collectionView.delegate = self
    collectionView.register(MainWithCarouselCollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
    collectionView.backgroundColor = UIColor.white
    self.view.addSubview(collectionView)

    let views = ["navBar":navBar,"collectionView": collectionView] as [String : Any]

    // 2
    var allConstraints = [NSLayoutConstraint]()

    let navBarHeight = NSLayoutConstraint.constraints(
        withVisualFormat: "H:|-0-[navBar]-0-|",
        options: [],
        metrics: nil,
        views: views)
    allConstraints += navBarHeight

    let navBarWidth = NSLayoutConstraint.constraints(
        withVisualFormat: "V:|-20-[navBar]",
        options: [],
        metrics: nil,
        views: views)
    allConstraints += navBarWidth


    let collectionViewTop = NSLayoutConstraint.constraints(
        withVisualFormat: "V:[navBar]-10-[collectionView]-|",
        options: [],
        metrics: nil,
        views: views)
    allConstraints += collectionViewTop


    let collectionViewleftRight = NSLayoutConstraint.constraints(
        withVisualFormat: "H:|-5-[collectionView]-5-|",
        options: [],
        metrics: nil,
        views: views)
    allConstraints += collectionViewleftRight

    navBar.translatesAutoresizingMaskIntoConstraints=false
    collectionView.translatesAutoresizingMaskIntoConstraints=false

    NSLayoutConstraint.activate(allConstraints)
    // Do any additional setup after loading the view.
}


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

    return 20
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {


    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! MainWithCarouselCollectionViewCell

    cell.labelicerik = "\(indexPath.row)"

   print(indexPath.row)
    return cell
}


func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width:view.frame.width,height: 150)
}
}

MainWithCarouselCollectionViewCell.swift

import UIKit

class MainWithCarouselCollectionViewCell: UICollectionViewCell,UICollectionViewDelegateFlowLayout,UICollectionViewDataSource,UICollectionViewDelegate {

    private let cellId = "Cell2"


    var labelicerik:String = {
        return ""
    }()

    let appsCollectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        layout.scrollDirection = .horizontal
        return collectionView
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)

        setupViews()

    }


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

    func setupViews() {
        backgroundColor = .blue

        addSubview(appsCollectionView)

        appsCollectionView.delegate = self
        appsCollectionView.dataSource = self


        appsCollectionView.register(AppCell.self, forCellWithReuseIdentifier: cellId)


        let views = ["appsCollectionView": appsCollectionView]  as [String : Any]

        // 2
        var allConstraints = [NSLayoutConstraint]()



        let collectionViewTop = NSLayoutConstraint.constraints(
            withVisualFormat: "H:|-0-[appsCollectionView]-0-|",
            options: [],
            metrics: nil,
            views: views)
        allConstraints += collectionViewTop


        let collectionViewleftRight = NSLayoutConstraint.constraints(
            withVisualFormat: "V:|-0-[appsCollectionView]-0-|",
            options: [],
            metrics: nil,
            views: views)
        allConstraints += collectionViewleftRight



        appsCollectionView.translatesAutoresizingMaskIntoConstraints=false
        NSLayoutConstraint.activate(allConstraints)


    }



    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 15
    }

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

        cell.testlabel.text = "\(labelicerik) + \(indexPath.row) "


        print(indexPath.row)
        print(labelicerik)
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
           return CGSize(width:contentView.frame.width/2,height: contentView.frame.height)
    }
}


class AppCell: UICollectionViewCell {

    let testlabel: UILabel = {

        let testlabel = UILabel(frame: .zero)


        return testlabel
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupViews()
    }

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

    func setupViews(){
        backgroundColor = .red
        addSubview(testlabel)

        testlabel.textAlignment = .center
        let views = ["testlabel": testlabel]  as [String : Any]

        // 2
        var allConstraints = [NSLayoutConstraint]()



        let collectionViewTop = NSLayoutConstraint.constraints(
            withVisualFormat: "H:|-0-[testlabel]-0-|",
            options: [],
            metrics: nil,
            views: views)
        allConstraints += collectionViewTop


        let collectionViewleftRight = NSLayoutConstraint.constraints(
            withVisualFormat: "V:|-0-[testlabel]-0-|",
            options: [],
            metrics: nil,
            views: views)
        allConstraints += collectionViewleftRight

        testlabel.translatesAutoresizingMaskIntoConstraints=false
        NSLayoutConstraint.activate(allConstraints)

    }
}

Answer 1

每次显示时都需要重新加载内部 Collection View

   func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
   let cell = collectionView.dequeueReusableCell(withReuseIdentifier:    "Cell", for: indexPath) as! MainWithCarouselCollectionViewCell
   cell.labelicerik = "\(indexPath.row)"
     // you need to call this
   cell.appsCollectionView.reloadData
   return cell
  }