UICollectionView Drag and Drop cell - swift

Question

Hi I want to do drag drop using uicollectionview. When performing drag and drop it is moving contents i want to do it like in the photo. I want the box to carry itself. For example; when I drag the photo to 4 I should leave the red area with full measurements. Swap photo 6 to photo 1 like taking photo 3 to the left. I have researched in uicollectionview so much but I can’t find anything like this. Please help me
import UIKit
final class ViewController: UIViewController {
#IBOutlet weak var collectionView: UICollectionView!
var cellIds = ["image 1","image 2","image 3","image 4","image 5","6","7"]
override func viewDidLoad() {
super.viewDidLoad()
let flowLayout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
flowLayout.estimatedItemSize = CGSize(width: 200, height: 10)
let gestureRecognizer = UILongPressGestureRecognizer(target: self,
action: #selector(self.handleLongPress(gestureRecognizer:)))
collectionView.addGestureRecognizer(gestureRecognizer)
}
#objc func handleLongPress(gestureRecognizer: UILongPressGestureRecognizer) {
guard let view = gestureRecognizer.view else { return }
let location = gestureRecognizer.location(in: view)
switch gestureRecognizer.state {
case .began:
guard let selectedIndexPath = collectionView.indexPathForItem(at: location) else { break }
collectionView.beginInteractiveMovementForItem(at: selectedIndexPath)
case .changed:
collectionView.updateInteractiveMovementTargetPosition(location)
case .ended:
collectionView.endInteractiveMovement()
default:
collectionView.cancelInteractiveMovement()
}
}
}
extension ViewController: UICollectionViewDataSource,
UICollectionViewDelegateFlowLayout
{
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return cellIds.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "SampleCell", for: indexPath) as! SampleCell
let text = cellIds[indexPath.item]
cell.label.text = text
return cell
}
func collectionView(_ collectionView: UICollectionView, canMoveItemAt indexPath: IndexPath) -> Bool {
return true
}
func collectionView(_ collectionView: UICollectionView, moveItemAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
let text = cellIds.remove(at: sourceIndexPath.item)
cellIds.insert(text, at: destinationIndexPath.item)
collectionView.reloadData()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if (indexPath.row==0)
{
return CGSize(width: 190, height: 100)
}
if (indexPath.row==1)
{
return CGSize(width: 190, height: 100)
}
if (indexPath.row==2)
{
return CGSize(width: 190, height: 400)
}
if (indexPath.row==3)
{
return CGSize(width: 400, height: 200)
}
return CGSize(width: 0, height: 0)
}
}
final class SampleCell: UICollectionViewCell {
#IBOutlet weak var label: UILabel!
override func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
setNeedsLayout()
layoutIfNeeded()
let size = self.systemLayoutSizeFitting(layoutAttributes.size)
var newFrame = layoutAttributes.frame
// note: don't change the width
newFrame.size.height = ceil(size.height)
layoutAttributes.frame = newFrame
return layoutAttributes
}
}
picture

Answer 1

You can use UICollectionViewDragDelegate,
For multiple sections, in order to drag to the end item, we should add an extra item when dragging.
Sample Code:
ViewController:
import UIKit
enum CellModel {
case simple(text: String)
case availableToDropAtEnd
}
class SecondController: UIViewController {
private lazy var cellIdentifier = "cellIdentifier"
private lazy var supplementaryViewIdentifier = "supplementaryViewIdentifier"
private lazy var sections = 10
private lazy var itemsInSection = 2
private lazy var numberOfElementsInRow = 3
private lazy var data: [[CellModel]] = {
var count = 0
return (0 ..< sections).map { _ in
return (0 ..< itemsInSection).map { _ -> CellModel in
count += 1
return .simple(text: "cell \(count)")
}
}
}()
override func viewDidLoad() {
super.viewDidLoad()
let collectionViewFlowLayout = UICollectionViewFlowLayout()
collectionViewFlowLayout.minimumLineSpacing = 5
collectionViewFlowLayout.minimumInteritemSpacing = 5
let _numberOfElementsInRow = CGFloat(numberOfElementsInRow)
let allWidthBetwenCells = _numberOfElementsInRow == 0 ? 0 : collectionViewFlowLayout.minimumInteritemSpacing*(_numberOfElementsInRow-1)
let width = (view.frame.width - allWidthBetwenCells)/_numberOfElementsInRow
collectionViewFlowLayout.itemSize = CGSize(width: width, height: width)
collectionViewFlowLayout.headerReferenceSize = CGSize(width: 0, height: 40)
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: collectionViewFlowLayout)
collectionView.backgroundColor = .white
view.addSubview(collectionView)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
collectionView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
collectionView.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor).isActive = true
collectionView.rightAnchor.constraint(equalTo: view.safeAreaLayoutGuide.rightAnchor).isActive = true
collectionView.register(CollectionViewCell.self, forCellWithReuseIdentifier: cellIdentifier)
collectionView.register(SupplementaryView.self,
forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,
withReuseIdentifier: supplementaryViewIdentifier)
collectionView.dragInteractionEnabled = true
collectionView.reorderingCadence = .fast
collectionView.dropDelegate = self
collectionView.dragDelegate = self
collectionView.delegate = self
collectionView.dataSource = self
}
}
extension SecondController: UICollectionViewDelegate { }
extension SecondController: UICollectionViewDataSource {
func numberOfSections(in collectionView: UICollectionView) -> Int {
return data.count
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return data[section].count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as! CollectionViewCell
switch data[indexPath.section][indexPath.item] {
case .simple(let text):
cell.label?.text = text
cell.backgroundColor = .gray
case .availableToDropAtEnd:
cell.backgroundColor = UIColor.green.withAlphaComponent(0.3)
}
return cell
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
return collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: supplementaryViewIdentifier, for: indexPath)
}
}
extension SecondController: UICollectionViewDragDelegate {
func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
let itemProvider = NSItemProvider(object: "\(indexPath)" as NSString)
let dragItem = UIDragItem(itemProvider: itemProvider)
dragItem.localObject = data[indexPath.section][indexPath.row]
return [dragItem]
}
func collectionView(_ collectionView: UICollectionView, itemsForAddingTo session: UIDragSession, at indexPath: IndexPath, point: CGPoint) -> [UIDragItem] {
let itemProvider = NSItemProvider(object: "\(indexPath)" as NSString)
let dragItem = UIDragItem(itemProvider: itemProvider)
dragItem.localObject = data[indexPath.section][indexPath.row]
return [dragItem]
}
func collectionView(_ collectionView: UICollectionView, dragSessionWillBegin session: UIDragSession) {
var itemsToInsert = [IndexPath]()
(0 ..< data.count).forEach {
itemsToInsert.append(IndexPath(item: data[$0].count, section: $0))
data[$0].append(.availableToDropAtEnd)
}
collectionView.insertItems(at: itemsToInsert)
}
func collectionView(_ collectionView: UICollectionView, dragSessionDidEnd session: UIDragSession) {
var removeItems = [IndexPath]()
for section in 0..<data.count {
for item in 0..<data[section].count {
switch data[section][item] {
case .availableToDropAtEnd:
removeItems.append(IndexPath(item: item, section: section))
case .simple:
break
}
}
}
removeItems.forEach { data[$0.section].remove(at: $0.item) }
collectionView.deleteItems(at: removeItems)
}
}
extension SecondController: UICollectionViewDropDelegate {
func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator) {
let destinationIndexPath: IndexPath
if let indexPath = coordinator.destinationIndexPath {
destinationIndexPath = indexPath
} else {
// useless, just in case
let section = collectionView.numberOfSections - 1
let row = collectionView.numberOfItems(inSection: section)
destinationIndexPath = IndexPath(row: row, section: section)
}
switch coordinator.proposal.operation {
case .move:
reorderItems(coordinator: coordinator, destinationIndexPath:destinationIndexPath, collectionView: collectionView)
default:
break
}
}
func collectionView(_ collectionView: UICollectionView, canHandle session: UIDropSession) -> Bool {
return true
}
func collectionView(_ collectionView: UICollectionView, dropSessionDidUpdate session: UIDropSession, withDestinationIndexPath destinationIndexPath: IndexPath?) -> UICollectionViewDropProposal {
// made the above logic useless
if collectionView.hasActiveDrag, destinationIndexPath != nil {
return UICollectionViewDropProposal(operation: .move, intent: .insertAtDestinationIndexPath)
}
else {
return UICollectionViewDropProposal(operation: .forbidden)
}
}
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,
let localObject = item.dragItem.localObject as? CellModel {
collectionView.performBatchUpdates ({
data[sourceIndexPath.section].remove(at: sourceIndexPath.item)
data[destinationIndexPath.section].insert(localObject, at: destinationIndexPath.item)
collectionView.deleteItems(at: [sourceIndexPath])
collectionView.insertItems(at: [destinationIndexPath])
})
}
}
}
View:
import UIKit
class CollectionViewCell: UICollectionViewCell {
weak var label: UILabel?
override init(frame: CGRect) {
super.init(frame: frame)
clipsToBounds = true
let label = UILabel(frame: .zero)
label.contentMode = .scaleAspectFill
addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
label.topAnchor.constraint(equalTo: topAnchor).isActive = true
label.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
label.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
label.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
label.textAlignment = .center
label.textColor = .white
self.label = label
layer.borderWidth = 1
layer.borderColor = UIColor.white.cgColor
backgroundColor = .white
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func prepareForReuse() {
super.prepareForReuse()
label?.text = nil
backgroundColor = .white
}
}
class SupplementaryView: UICollectionReusableView {
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = UIColor.blue.withAlphaComponent(0.7)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
github link