【发布时间】：2018-03-03 10:41:09
【问题描述】：
我正在开发一个应用程序，我可以在其中跟踪我的青年足球队的替换情况。
按照Payal Gupta 的关于拖放到集合和表格中的教程，我设法在两个集合视图（PlayersOntoTheField 和 Substitutes）之间进行拖放操作 Screenshot。
当我将一名替补球员拖入我的操场时，它现在应该会捕捉到预定义的球队阵容（例如屏幕截图中的 3-2-1）。是否有可能通过自定义 UICollectionViewLayout 获得这种行为，或者有人有其他建议吗？
非常感谢您提前提供的任何帮助。
丹尼
//Based on a work by:
//Payal Gupta (https://github.com/pgpt10/DragAndDrop-CollectionView)
import UIKit
class ViewController: UIViewController
{
private var substitutes = ["player1", "player2", "player3", "player4"]
private var players = [String]()
@IBOutlet weak var substitutesCollectionView: UICollectionView!
@IBOutlet weak var playersCollectionView: UICollectionView!
override func viewDidLoad()
{
super.viewDidLoad()
//SubstitutesCollectionView drag and drop configuration
self.substitutesCollectionView.dragInteractionEnabled = true
self.substitutesCollectionView.dragDelegate = self
self.substitutesCollectionView.dropDelegate = self
//PlayersCollectionView drag and drop configuration
self.playersCollectionView.dragInteractionEnabled = true
self.playersCollectionView.dropDelegate = self
self.playersCollectionView.dragDelegate = self
self.playersCollectionView.reorderingCadence = .fast //default value - .immediate
}
//MARK: Private Methods
private func reorderItems(coordinator: UICollectionViewDropCoordinator, destinationIndexPath: IndexPath, collectionView: UICollectionView)
{
let items = coordinator.items
if items.count == 1, let item = items.first, let sourceIndexPath = item.sourceIndexPath
{
var dIndexPath = destinationIndexPath
if dIndexPath.row >= collectionView.numberOfItems(inSection: 0)
{
dIndexPath.row = collectionView.numberOfItems(inSection: 0) - 1
}
collectionView.performBatchUpdates({
if collectionView === self.playersCollectionView
{
self.players.remove(at: sourceIndexPath.row)
self.players.insert(item.dragItem.localObject as! String, at: dIndexPath.row)
}
else
{
self.substitutes.remove(at: sourceIndexPath.row)
self.substitutes.insert(item.dragItem.localObject as! String, at: dIndexPath.row)
}
collectionView.deleteItems(at: [sourceIndexPath])
collectionView.insertItems(at: [dIndexPath])
})
coordinator.drop(items.first!.dragItem, toItemAt: dIndexPath)
}
}
private func copyItems(coordinator: UICollectionViewDropCoordinator, destinationIndexPath: IndexPath, collectionView: UICollectionView)
{
collectionView.performBatchUpdates({
var indexPaths = [IndexPath]()
for (index, item) in coordinator.items.enumerated()
{
let indexPath = IndexPath(row: destinationIndexPath.row + index, section: destinationIndexPath.section)
if collectionView === self.playersCollectionView
{
self.players.insert(item.dragItem.localObject as! String, at: indexPath.row)
}
else
{
self.substitutes.insert(item.dragItem.localObject as! String, at: indexPath.row)
}
indexPaths.append(indexPath)
}
collectionView.insertItems(at: indexPaths)
})
}
}
// MARK: - UICollectionViewDataSource Methods
extension ViewController : UICollectionViewDataSource
{
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
{
return collectionView == self.substitutesCollectionView ? self.substitutes.count : self.players.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
{
if collectionView == self.substitutesCollectionView
{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell1", for: indexPath) as! MyCollectionViewCell
cell.customImageView?.image = UIImage(named: self.substitutes[indexPath.row])
cell.customLabel.text = self.substitutes[indexPath.row].capitalized
return cell
}
else
{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell2", for: indexPath) as! MyCollectionViewCell
cell.customImageView?.image = UIImage(named: self.players[indexPath.row])
cell.customLabel.text = self.players[indexPath.row].capitalized
return cell
}
}
}
// MARK: - UICollectionViewDragDelegate Methods
extension ViewController : UICollectionViewDragDelegate
{
func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem]
{
let item = collectionView == substitutesCollectionView ? self.substitutes[indexPath.row] : self.players[indexPath.row]
let itemProvider = NSItemProvider(object: item as NSString)
let dragItem = UIDragItem(itemProvider: itemProvider)
dragItem.localObject = item
return [dragItem]
}
func collectionView(_ collectionView: UICollectionView, itemsForAddingTo session: UIDragSession, at indexPath: IndexPath, point: CGPoint) -> [UIDragItem]
{
let item = collectionView == substitutesCollectionView ? self.substitutes[indexPath.row] : self.players[indexPath.row]
let itemProvider = NSItemProvider(object: item as NSString)
let dragItem = UIDragItem(itemProvider: itemProvider)
dragItem.localObject = item
return [dragItem]
}
func collectionView(_ collectionView: UICollectionView, dragPreviewParametersForItemAt indexPath: IndexPath) -> UIDragPreviewParameters?
{
if collectionView == substitutesCollectionView
{
let previewParameters = UIDragPreviewParameters()
previewParameters.visiblePath = UIBezierPath(rect: CGRect(x: 15, y: 5, width: 30, height: 30))
return previewParameters
}
return nil
}
}
// MARK: - UICollectionViewDropDelegate Methods
extension ViewController : UICollectionViewDropDelegate
{
func collectionView(_ collectionView: UICollectionView, canHandle session: UIDropSession) -> Bool
{
return session.canLoadObjects(ofClass: NSString.self)
}
func collectionView(_ collectionView: UICollectionView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UICollectionViewDropProposal
{
if collectionView === self.substitutesCollectionView
{
if collectionView.hasActiveDrag
{
return UICollectionViewDropProposal(operation: .move, intent: .insertAtDestinationIndexPath)
}
else
{
return UICollectionViewDropProposal(operation: .forbidden)
}
}
else
{
if collectionView.hasActiveDrag
{
return UICollectionViewDropProposal(operation: .move, intent: .insertAtDestinationIndexPath)
}
else
{
return UICollectionViewDropProposal(operation: .copy, intent: .insertAtDestinationIndexPath)
}
}
}
func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator)
{
let destinationIndexPath: IndexPath
if let indexPath = coordinator.destinationIndexPath
{
destinationIndexPath = indexPath
}
else
{
// Get last index path of table view.
let section = collectionView.numberOfSections - 1
let row = collectionView.numberOfItems(inSection: section)
destinationIndexPath = IndexPath(row: row, section: section)
}
switch coordinator.proposal.operation
{
case .move:
self.reorderItems(coordinator: coordinator, destinationIndexPath:destinationIndexPath, collectionView: collectionView)
break
case .copy:
self.copyItems(coordinator: coordinator, destinationIndexPath: destinationIndexPath, collectionView: collectionView)
default:
return
}
}
}
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标签： swift drag-and-drop uicollectionview uicollectionviewlayout custom-view