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「Swift」类似微信九宫格图片任意拖拽图片更改顺序
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前言：需要完成一个UGC添加图片，并且可以实现图片任意拖拽更改图片顺序的需求
需求分析：添加图片需要用到UICollectionView，然后添加图片用使用UICollectionView的系统方法进行实现开始拖拽的记录，拖拽过程中的处理，拖拽放下的处理
贴代码：
class collectionViewDragAndDropViewController: BaseViewController {
private var myCollectionView: UICollectionView!
/// 开始拖动时的数据暂存
private var dragingIndexPath: IndexPath?
private var imageList = [UIImage.image(.fruit_lemon),
UIImage.image(.fruit_mango),
UIImage.image(.fruit_litchi),
UIImage.image(.fruit_orange),
UIImage.image(.fruit_raspberry),
UIImage.image(.fruit_strawberry),
UIImage.image(.fruit_watermelon),
UIImage.image(.fruit_blueberries)]
override func viewDidLoad() {
super.viewDidLoad()
setupNav()
initView()
setupLayout()
}
private func setupNav() {
isNavBarisTranslucent = true
isNavBarisHidden = false
setBarButtonItem(.image(UIImage.image(.back_icon), size: CGSize(width: 44, height: 44)), RightBarButtonItemType.none)
}
override func leftItemAction() {
self.navigationController?.popViewController(animated: true)
}
private func initView() {
self.view.backgroundColor = UIColor.color(.color_FFFFFF)
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical
myCollectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
myCollectionView.showsVerticalScrollIndicator = false
myCollectionView.delegate = self
myCollectionView.dataSource = self
myCollectionView.dragInteractionEnabled = true
myCollectionView.dragDelegate = self
myCollectionView.dropDelegate = self
myCollectionView.register(myCollectionViewCell.self, forCellWithReuseIdentifier: NSStringFromClass(myCollectionViewCell.self))
self.view.addSubview(myCollectionView)
}
private func setupLayout() {
myCollectionView.snp.makeConstraints { make in
make.top.equalTo(Common.navigatorHeight).offset(8.fit())
make.left.equalTo(16.fit())
make.right.equalTo(-16.fit())
make.bottom.equalTo(self.view)
}
}
}
extension collectionViewDragAndDropViewController: UICollectionViewDelegate,
UICollectionViewDataSource,
UICollectionViewDelegateFlowLayout {
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 8
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let row = indexPath.row
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: NSStringFromClass(myCollectionViewCell.self), for: indexPath) as! myCollectionViewCell
cell.updateCellBgImageView(image: self.imageList[row])
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: (Common.screenWidth - 52.fit()) / 3, height: (Common.screenWidth - 52.fit()) / 3)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return .zero
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 10.fit()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
}
extension collectionViewDragAndDropViewController: UICollectionViewDragDelegate {
///处理首次拖动时，是否响应
func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
/// 如果是最后一个Cell，不响应拖动事件
if indexPath.row == 7 {
return []
}
let row = indexPath.row
let item = self.imageList[row]
let itemProvider = NSItemProvider(object: item)
let dragItem = UIDragItem(itemProvider: itemProvider)
dragItem.localObject = item
dragingIndexPath = indexPath
return [dragItem]
}
}
extension collectionViewDragAndDropViewController: UICollectionViewDropDelegate {
///处理拖动放下后如何处理
func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator) {
guard let destinationIndexPath = coordinator.destinationIndexPath else {
return
}
switch coordinator.proposal.operation {
case .move:
let items = coordinator.items
if let item = items.first, let sourceIndexPath = item.sourceIndexPath {
//执行批量更新
myCollectionView.performBatchUpdates({
self.imageList.remove(at: sourceIndexPath.row)
self.imageList.insert(item.dragItem.localObject as! UIImage, at: destinationIndexPath.row)
myCollectionView.deleteItems(at: [sourceIndexPath])
myCollectionView.insertItems(at: [destinationIndexPath])
})
//将项目动画化到视图层次结构中的任意位置
coordinator.drop(item.dragItem, toItemAt: destinationIndexPath)
}
break
default:
return
}
}
///处理拖动过程中
func collectionView(_ collectionView: UICollectionView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UICollectionViewDropProposal {
if self.imageList.count
if collectionView.hasActiveDrag {
return UICollectionViewDropProposal(operation: .move, intent: .insertAtDestinationIndexPath)
} else {
return UICollectionViewDropProposal(operation: .copy, intent: .insertAtDestinationIndexPath)
}
} else {
return UICollectionViewDropProposal(operation: .forbidden)
}
}
}
效果图：
ps：因为设定数组最后一个cell不能进行拖动，所以动图最后无法移动蓝莓图片(此功能用于如添加图片的Cell无法进行移动的情况) |
整理不易，望对大家有所帮助，多多点赞，谢谢大家！【本文地址】
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