UICollectionView 在 iOS 16 beta 上移动项目时崩溃

Question

我有一个UICollectionView ，用户可以在其中长按然后移动项目。 我已经实现了func invalidationContext(forInteractivelyMovingItems和func invalidationContextForEndingInteractiveMovementOfItems方法来处理这个问题。

在 iOS 16 beta 上进行测试时，移动项目时应用程序崩溃。 根本原因是previousIndexPaths和targetIndexPaths在下面的代码中都变成了 nil。 知道为什么会这样吗？ 在 < iOS16 上工作正常。

open override func invalidationContext(forInteractivelyMovingItems targetIndexPaths: [IndexPath], withTargetPosition targetPosition: CGPoint, previousIndexPaths: [IndexPath], previousPosition: CGPoint) -> UICollectionViewLayoutInvalidationContext {
    
    let context = super.invalidationContext(forInteractivelyMovingItems: targetIndexPaths, withTargetPosition: targetPosition, previousIndexPaths: previousIndexPaths, previousPosition: previousPosition)
    
    //Check that the movement has actually happeneds
    if previousIndexPaths.first!.item != targetIndexPaths.first!.item {
        collectionView?.dataSource?.collectionView?(collectionView!, moveItemAt: previousIndexPaths.first!, to: targetIndexPaths.last!)
    }
    
    return context
}

open override func invalidationContextForEndingInteractiveMovementOfItems(toFinalIndexPaths indexPaths: [IndexPath], previousIndexPaths: [IndexPath], movementCancelled: Bool) -> UICollectionViewLayoutInvalidationContext {
    return super.invalidationContextForEndingInteractiveMovementOfItems(toFinalIndexPaths: indexPaths, previousIndexPaths: previousIndexPaths, movementCancelled: movementCancelled)
}

UICollectionView移动项目的委托方法

func collectionView(_ collectionView: UICollectionView, moveItemAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {

    if self.longPressGesture.state == .ended {
        self.collectionView.reloadData()
        return
    }

    let cell = self.availableItems[sourceIndexPath.item]
    self.availableItems.remove(at: sourceIndexPath.item)
    self.availableItems.insert(cell, at: destinationIndexPath.item)
}

在 iOS 16 previousIndexPaths和targetIndexPaths为 nil

On iOS 15 previousIndexPaths和targetIndexPaths都有值

Answer 1

只需添加一个延迟，它现在就可以在 iOS 16 上为我工作。

DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
            collectionView.beginInteractiveMovementForItem(at: selectedIndexPath)
        }