Swift下使用UICollectionView 实现长按拖拽功能

导读

简单用Swift写了一个collectionview的拖拽点击排序效果;

拖拽排序是新闻类的App可以说是必有的交互设计，如今日头条，网易新闻等。

GitHub地址：https://github.com/wangliujiayou/Swift-dragLabel 欢迎Star.

效果

主要代码

手势长按移动

1.给CollectionViewCell添加一个长按手势.

private lazy var collectionView: UICollectionView = {
  let clv = UICollectionView(frame: self.view.frame, collectionViewLayout: ChannelViewLayout())
  clv.backgroundColor = UIColor.white
  clv.delegate = self
  clv.dataSource = self
  clv.register(ChannelViewCell.self, forCellWithReuseIdentifier: ChannelViewCellIdentifier)
  clv.register(ChannelHeaderView.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: ChannelViewHeaderIdentifier)
  let longPress = UILongPressGestureRecognizer(target: self, action: #selector(longPressGesture(_:)))
  clv.addGestureRecognizer(longPress)
  return clv
 }()

2.开始长按时对cell进行截图或拷贝一个cell，并隐藏cell.

 //MARK: - 长按开始
 private func dragBegan(point: CGPoint) {
  indexPath = collectionView.indexPathForItem(at: point)
  if indexPath == nil || (indexPath?.section)! > 0 || indexPath?.item == 0
  {return}
  let item = collectionView.cellForItem(at: indexPath!) as? ChannelViewCell
  item?.isHidden = true
  dragingItem.isHidden = false
  dragingItem.frame = (item?.frame)!
  dragingItem.text = item!.text
  //放大效果(此处可以根据需求随意修改)
  dragingItem.transform = CGAffineTransform(scaleX: 1.1, y: 1.1)
 }

3.在手势移动的时候，找到目标是的indexPatch，再调用系统的api交换这个cell和隐藏cell的位置，并且更新数据.

 //MARK: - 移动过程
 private func drageChanged(point: CGPoint) {
  if indexPath == nil || (indexPath?.section)! > 0 || indexPath?.item == 0 {return}
  dragingItem.center = point
  targetIndexPath = collectionView.indexPathForItem(at: point)
  if targetIndexPath == nil || (targetIndexPath?.section)! > 0 || indexPath == targetIndexPath || targetIndexPath?.item == 0 {return}
  // 更新数据
  let obj = selectedArr[indexPath!.item]
  selectedArr.remove(at: indexPath!.row)
  selectedArr.insert(obj, at: targetIndexPath!.item)
  //交换位置
  collectionView.moveItem(at: indexPath!, to: targetIndexPath!)
  //进行记录
  indexPath = targetIndexPath
 }

4.手势停止或取消时，移除view，显示隐藏cell. (这里手势取消也要掉用此方法)

//MARK: - 长按结束或取消
 private func drageEnded(point: CGPoint) {
  if indexPath == nil || (indexPath?.section)! > 0 || indexPath?.item == 0 {return}
  let endCell = collectionView.cellForItem(at: indexPath!)
  UIView.animate(withDuration: 0.25, animations: {
   self.dragingItem.transform = CGAffineTransform.identity
   self.dragingItem.center = (endCell?.center)!
  }, completion: {
   (finish) -> () in
   endCell?.isHidden = false
   self.dragingItem.isHidden = true
   self.indexPath = nil
  })
 }

点击移动

collectionView的点击方法,我这里分为两段,第一段为点击处理事件,第二段为点击添加添加标签(编辑状态下第一段可以点击排序)

 func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
  if indexPath.section > 0 {
   // 更新数据
   let obj = recommendArr[indexPath.item]
   recommendArr.remove(at: indexPath.item)
   selectedArr.append(obj)
   //移动方法
   collectionView.moveItem(at: indexPath, to: NSIndexPath(item: selectedArr.count - 1, section: 0) as IndexPath)
  } else {
   if isEdite {
    if indexPath.item == 0 {return}
    // 更新数据
    let obj = selectedArr[indexPath.item]
    selectedArr.remove(at: indexPath.item)
    recommendArr.insert(obj, at: 0)
    //移动方法
    collectionView.moveItem(at: indexPath, to: NSIndexPath(item: 0, section: 1) as IndexPath)
   } else {
    if switchoverCallback != nil {
     //处理点击的闭包
     switchoverCallback!(selectedArr, recommendArr, indexPath.item)
     _ = navigationController?.popViewController(animated: true)
    }
   }
  }
 }

其他

此代码只是一个效果,没有怎么封装,如果仔细看过的朋友可以知道其实没有多么复杂

点击移动

collectionView.moveItem(at: indexPath, to: NSIndexPath(item: 0, section: 1) as IndexPath)

拖拽移动

collectionView.moveItem(at: indexPath!, to: targetIndexPath!)

主要就是这两个方法,其他都是处理逻辑以及视图效果.

提示

如果你们是从iOS9开始适配的话，那么可以用系统的Api，非常简单好用,大家这里可以自己去试试.

 // Support for reordering
 @available(iOS 9.0, *)
 open func beginInteractiveMovementForItem(at indexPath: IndexPath) -> Bool // returns NO if reordering was prevented from beginning - otherwise YES
 @available(iOS 9.0, *)
 open func updateInteractiveMovementTargetPosition(_ targetPosition: CGPoint)
 @available(iOS 9.0, *)
 open func endInteractiveMovement()
 @available(iOS 9.0, *)
 open func cancelInteractiveMovement()

源码可以从这里下载

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