Swift基础之仿资讯类实现频道的长按拖拽／删除／增加

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。

效果

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()