I have two sections in my UICollectionView. I would like to be able to drag cells within each section but not between them.
I am using a long press gesture recognizer to animate the cell drag movement so I could check that the drop location is not in a different section. Is there a way to determine a section's frame?
Or is there a simpler way?
在 中UICollectionViewDropDelegate，此协议func collectionView(_ collectionView: UICollectionView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UICollectionViewDropProposal可以提供帮助。
检查下面的示例，了解如何防止将项目从一个部分拖到另一部分：
在UICollectionViewDragDelegate中，我们使用该itemsForBeginning函数来传递有关对象的信息。您可以看到，我将索引和项目传递给localObject
func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
let item = sectionViewModel[indexPath.section].items[indexPath.row]
let itemProvider = NSItemProvider(object: item.title as NSString)
let dragItem = UIDragItem(itemProvider: itemProvider)
dragItem.localObject = (item, indexPath)
return [dragItem]
}
在UICollectionViewDropDelegate中，我这样做了：
func collectionView(_ collectionView: UICollectionView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UICollectionViewDropProposal {
if let object = session.items.first?.localObject as? (Item, IndexPath), object.0.status, let destinationIndexPath = destinationIndexPath, object.1.section == destinationIndexPath.section {
let itemAtDestination = sectionViewModel[destinationIndexPath.section].items[destinationIndexPath.row]
if itemAtDestination.status {
return UICollectionViewDropProposal(operation: .move, intent: .insertAtDestinationIndexPath)
}
}
return UICollectionViewDropProposal(operation: .forbidden)
}
根据苹果：
当用户拖动内容时，collection view 会重复调用这个方法来确定如果它发生在指定位置，你将如何处理它。集合视图根据您的建议向用户提供视觉反馈。在此方法的实现中，创建一个 UICollectionViewDropProposal 对象并使用它来传达您的意图。因为在用户拖动表格视图时会重复调用此方法，所以您的实现应该尽快返回。
我做了什么：我有几个限制要涵盖：
动图
