当collectionView动画与另一个视图耦合时，错误的单元格框架

Question

正如标题所示，我将说明重现我的情况所需的最低限度。

我的导航控制器中嵌入了我的FakeViewController。它包含：

• 在故事板上创建的顶视图和collectionView（请参阅图像了解约束）
• 在代码中使用hidesNavigationBarDuringPresentation = true分配给navigationItem的搜索控制器。

单元格必须占据整个collectionView边界（如pageViewController），它会显示一个简单的viewController.view（图中浅蓝色）。

在viewDidLoad，一切都很好。当我点击searchBar时，导航栏消失，顶视图和collectionView向上移动。

但是当我点击取消按钮时，单元格仍然位于隐藏其内容部分的顶视图下方。

控制台打印：

The relevant UICollectionViewFlowLayout instance is <UICollectionViewFlowLayout: 0x7fefc6463b10>, and it is attached to <UICollectionView: 0x7fefc78a2000; frame = (0 180; 375 438); clipsToBounds = YES; autoresize = RM+BM; gestureRecognizers = <NSArray: 0x604000a48fd0>; layer = <CALayer: 0x60400022df20>; contentOffset: {0, 0}; contentSize: {375, 484}; adjustedContentInset: {0, 0, 0, 0}> collection view layout: <UICollectionViewFlowLayout: 0x7fefc6463b10>.

Make a symbolic breakpoint at UICollectionViewFlowLayoutBreakForInvalidSizes to catch this in the debugger.

查看调试视图Hierarchy，我发现collectionView具有正确的框架，而其单元格没有更新它。 我不知道如何强制单元格缩短：尝试使用自定义UICollectionViewFlowLayout或在取消轻敲后调用invalidateLayout()，但问题仍然存在。

编辑：我忘了说topView是＆＃34;必需＆＃34;有问题

这是我的FakeViewControlelr实现：

class FakeViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate, UICollectionViewDataSource, UISearchBarDelegate {

//MARK: - Model
private var views = [UIView]()

//MARK: Outlets
@IBOutlet weak var collectionView: UICollectionView!
private var searchController = UISearchController(searchResultsController: nil)

override func viewDidLoad() {
    super.viewDidLoad()
    setupSearchController()
    setupCollectionView()
}

//MARK: - Helpers
private func setupSearchController() {
    searchController.obscuresBackgroundDuringPresentation = false
    definesPresentationContext = true
    searchController.searchBar.placeholder = "Search here"
    searchController.searchBar.delegate = self
    searchController.searchBar.searchBarStyle = .minimal
    searchController.hidesNavigationBarDuringPresentation = true
    navigationItem.searchController = searchController
    navigationItem.hidesSearchBarWhenScrolling = false
}

private func setupCollectionView() {
    guard let supersetListVC = self.storyboard?.instantiateViewController(withIdentifier: "SupersetListVC") else {return}
    self.addChildViewController(supersetListVC)
    self.views.append(supersetListVC.view)
    self.collectionView.delegate = self
    self.collectionView.dataSource = self
    searchController.searchBar.delegate = self
    self.collectionView.reloadData()
}

//MARK: - UICollectionViewDataSource
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return views.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
    let displayedView = self.views[indexPath.row]
    cell.contentView.addSubview(displayedView)
    displayedView.frame = cell.contentView.bounds
    return cell
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    //NOTICE: this method isn't called when navigationBar turns visible.
    //Thats why I implemented searchBarCancellButtonClicked(_:)
        return CGSize(width: collectionView.bounds.width, height: collectionView.bounds.height)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
}

func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
    self.collectionView.collectionViewLayout.invalidateLayout()
}

}

提前感谢您的帮助！ 亲切的问候 的Alessandro