使用swift从中删除项目后，CollectionView indexPath不会更新

Question

实际上，我为电子商务应用开发了愿望清单页面。愿望清单单元格包含一个爱（愿望清单）按钮。

要求

1. 点击Love（Wishlist）按钮
时删除单元格
2. 漂亮的删除动画



WishCell - 按钮单击部分

class WishCell: UICollectionViewCell {

    var wishButtonTapped : (() -> Void)? = nil

    @IBAction func wishBtnTapped(_ sender: Any) {
        if let wishBtnTap = wishButtonTapped {
            wishBtnTap()
        }
    }
}

CollectionView CellForRowAt

按钮单击在CellForRowAt中处理。

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "WishCell", for: indexPath) as? WishCell {

            cell.configureCell(wishlist: wishlists[indexPath.row])

            // Wish Button
            cell.wishButtonTapped = {
                print("indexPath", indexPath)
                print("indexPathRow", indexPath.row, wishlistJSON.count)

//                wishlistJSON.remove(at: indexPath.row)
//                self.parseWishlistJSON()
                self.wishlists.remove(at: indexPath.row)
                collectionView.deleteItems(at: [indexPath])
//                self.collectionView.reloadData()
                self.updateDesign()
            }
            return cell

        } else {
            return UICollectionViewCell()
        }
    }

打印日志

点击第三个单元格

indexPath [0, 2]
indexPathRow 2 5

再次点击第三个单元格

indexPath [0, 3]
indexPathRow 3 5

问题

1. 删除单元格后，collectionView的IndexPath没有更新
2. 在wishlistJSON.remove(at: indexPath.row)崩溃应用程序，因为数组indexOutOfBound

Answer 1

我遇到了同样的问题，对我来说，强制执行collectionView.reloadData（）可以解决问题。仍然不清楚为什么删除行不会更新单元格的IndexPath ...但是至少可以使它正常工作

Answer 2

When cells get reused, cell.wishButtonTapped actions will get added again! That's not what we want.

Protocols Approach solve this

protocol WishlistDelegate: class {
    func wishlistBtnTap(_ sender: WishCell)
}

WishCell

class WishCell: UICollectionViewCell {

    weak var delegate: WishlistDelegate?

    @IBAction func wishBtnTapped(_ sender: Any) {
        delegate?.wishlistBtnTap(self)
    }

CollectionView CellForRowAt

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "WishCell", for: indexPath) as? WishCell {

            cell.configureCell(wishlist: wishlists[indexPath.row])
            cell.delegate = self

            return cell

        } else {
            return UICollectionViewCell()
        }
    }

extension - WishlistDelegate

extension WishlistVC: WishlistDelegate {
    func wishlistBtnTap(_ sender: WishCell) {
        guard let tappedIndexPath = collectionView.indexPath(for: sender) else { return }

        // Delete the Item
        wishlists.remove(at: tappedIndexPath.row)
        collectionView.deleteItems(at: [tappedIndexPath])
    }
}

Answer 3

重新加载Collection-view必须要做到这一点

[self.collectionView performBatchUpdates:^{
    [self.collectionView reloadSections:[NSIndexSet indexSetWithIndex:0]];
}