嵌套集合视图单元格未在方向更改时调整大小

Posted 2021-04-21

外集合视图（在ViewController文件中）

• 占据屏幕的整个宽度和高度
• Cell还占据了屏幕的整个宽度和高度
• 集合视图布局是水平的。能够滑动到下一个单元格。
• 细胞背景是绿色的

嵌套集合视图（在UICollectionViewCell的文件中）

• 占据屏幕的整个宽度和高度
• Cell占据屏幕的整个宽度。身高是100，
• 细胞紫色背景。

问题

1. 我首先在Xcode的模拟器上以纵向方式运行应用程序。
2. 当我将方向更改为横向并滑动所有屏幕时，
3. 一个屏幕将有紫色单元格，不占用整个屏幕。此问题仅发生在横向中。

问题：总是有一个像这样的紫色单元格的屏幕

所有细胞如何看待定向景观

4. 如果没有出现问题，请将方向更改回纵向，然后将其更改为横向。然后再次扫描所有单元格以找到问题。

App Delagate

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        window = UIWindow()
        window?.makeKeyAndVisible()

        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal

        window?.rootViewController = ViewController(collectionViewLayout: layout)

        return true

    }

}

查看控制器

import UIKit

class ViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    override func viewDidLoad() {
        super.viewDidLoad()

        collectionView?.register(CollectionViewCell.self, forCellWithReuseIdentifier: "cellid")
        collectionView?.isPagingEnabled = true
    }

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

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellid", for: indexPath) as! CollectionViewCell
        return cell
    }

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

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }

    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        collectionViewLayout.invalidateLayout()
    }

}

集合视图单元格（具有嵌套集合视图）

import UIKit

class CollectionViewCell: UICollectionViewCell, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

    lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.backgroundColor = .green
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        collectionView.delegate = self
        collectionView.dataSource = self
        return collectionView
    }()

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

        backgroundColor = .purple

        addSubview(collectionView)

        collectionView.topAnchor.constraint(equalTo: topAnchor).isActive = true
        collectionView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
        collectionView.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
        collectionView.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true

        collectionView.register(InnerCell.self, forCellWithReuseIdentifier: "cellid")
    }

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

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 2
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellid", for: indexPath) as! InnerCell
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: frame.width, height: 100)
    }

}

内部单元格（嵌套集合视图的单元格）

import UIKit

class InnerCell: UICollectionViewCell {

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

        backgroundColor = .purple
    }

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

}

我在github https://github.com/vk99x/Nested-Collection-View上有这个项目

答案

 override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    collectionViewLayout.invalidateLayout()
    // Also try reloading your collection view to calculate the new constraints
    DispatchQueue.main.async{
        collectionView.reloadData()
    }
}

嘿检查这个，让我们看看它是否有帮助