swift - 如何在展开时保持 UICollectionviewcell 高度？

Question

我的 UIViewController 类中有一个 Collection View ，并使用 bool 数组来查看哪些索引已展开 (refer to this answer) .

var isExpanded = [Bool]()

因此，当我单击按钮时，我可以使用以下命令重新加载单元格:

@objc func topButtonTouched(indexPath: IndexPath) {
    print(indexPath)
    isExpanded[indexPath.row] = !isExpanded[indexPath.row]
    UIView.animate(withDuration: 0.6, delay: 0.0, usingSpringWithDamping: 0.6, initialSpringVelocity: 1.0, options: UIView.AnimationOptions.transitionCurlUp, animations: {
        self.listCollectionView.reloadItems(at: [indexPath])
    }, completion: { success in
        print("success")
    })
}

到目前为止一切顺利。但是，当单元格重新排序时，我遇到的问题就会出现。我不会使用 beginInteractiveMovementForItem()、updateInteractiveMovementTargetPosition() 等重新排序。

我开始使用这个功能(from this repository)下面创建一个缩放动画(单元格的快照)，认为它也会对单元格重新排序:

@objc func longPressRecognized(_ recognizer: UILongPressGestureRecognizer) {
    let location = recognizer.location(in: collectionView)
    let indexPath = collectionView.indexPathForItem(at: location)

    switch recognizer.state {
    case UIGestureRecognizer.State.began:
        guard let indexPath = indexPath else { return }

        let cell = cellForRow(at: indexPath)
        snapshotView = cell.snapshotView(afterScreenUpdates: true)
        collectionView.addSubview(snapshotView!)
        cell.contentView.alpha = 0.0

        UIView.animate(withDuration: 0.2, animations: {
            self.snapshotView?.transform = CGAffineTransform(scaleX: 1.1, y: 1.1)
            self.snapshotView?.alpha = 0.9
        })
        snapshotPanPoint = location
        snapshotIndexPath = indexPath
    case UIGestureRecognizer.State.changed:
        guard let snapshotPanPoint = snapshotPanPoint else { return }

        let translation = CGPoint(x: location.x - snapshotPanPoint.x, y: location.y - snapshotPanPoint.y)
        snapshotView?.center.y += translation.y
        self.snapshotPanPoint = location

        guard let indexPath = indexPath else { return }
        collectionView.moveItem(at: snapshotIndexPath!, to: indexPath)
        snapshotIndexPath = indexPath
    default:
        guard let snapshotIndexPath = snapshotIndexPath else { return }
        let cell = cellForRow(at: snapshotIndexPath)
        UIView.animate(
            withDuration: 0.2,
            animations: {
                self.snapshotView?.center = cell.center
                self.snapshotView?.transform = CGAffineTransform.identity
                self.snapshotView?.alpha = 1.0
        },
            completion: { finished in
                cell.contentView.alpha = 1.0
                self.snapshotView?.removeFromSuperview()
                self.snapshotView = nil
        })
        self.snapshotIndexPath = nil
        self.snapshotPanPoint = nil
    }
}

我尝试更改开关的 .changed 部分中的 isExpanded 数组，但没有成功。我也尝试过这个answer .

我的问题的动图:

编辑: 之前，当我有一个 bool 数组时，它是这样的:

@objc func topButtonTouched(indexPath: IndexPath) {
isExpanded[indexPath.item] = !isExpanded[indexPath.item]

现在有了主要的对象数组，我正在尝试这样做:

@objc func topButtonTouched(indexPath: IndexPath) {

    var names = mainData.map({ $0.isExpanded })
    names[indexPath.row] = !names[indexPath.row]

然后更新索引路径。

Answer 1

一般来说，在单个 UITableView 中使用多个数据源会带来坏运气，当您在计划更改项目顺序 - 这简直就是自杀:)

因此，我建议您将数据源从两个数组 - [String] 和 [Bool] 更改为单个 [ListItem] -

(这里我使用的是class，但你也可以使用struct，只要记住classes是由传递的引用，而结构通过值传递)

class ListItem{
    var title: String
    var isExpended: Bool

    init(title: String, isExpended: Bool){
        self.title = title
        self.isExpended = isExpended
    }
}

然后，当用户完成重新排序时，您需要在列表上提交这些更改 - 删除元素并将其插入到不同的索引即可完成这项工作。