Swift OSX - Rearrange NSCollectionView with drag and drop not working - swift

Question

I am trying to rearrange the item inside a NSCollectionView but it's not working. It doesn't call some delegate methods as validate drop and accept drop. It calls func collectionView(_ collectionView: NSCollectionView, pasteboardWriterForItemAt indexPath: IndexPath) -> NSPasteboardWriting? or func collectionView(_ collectionView: NSCollectionView, writeItemsAt indexPaths: Set<IndexPath>, to pasteboard: NSPasteboard) -> Bool, but after that is doesn't call the other methods.
I think the problem is that I am bot being able to register the correct types for the drag and drop because when I move the items inside the collection view it doesn't show a place where the items can be dropped and after I drop it the items bounce back to their original places.
Here is the code:
FotoProdutoLojaCollectionViewItem.swift
import Cocoa
class FotoProdutoLojaCollectionViewItem: NSCollectionViewItem {
#IBOutlet weak var fotoProdutoLojaImageView: NSImageView!
#IBOutlet weak var fotoCapaImageView: NSImageView!
override func viewDidLoad() {
super.viewDidLoad()
fotoCapaImageView.isHidden = true
}
}
The items of the CollectionView
func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
var item = NSCollectionViewItem()
item = collectionView.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "FotoProdutoLojaCollectionViewItem"), for: indexPath)
let fotosProdutoLojaCollectionViewItem = item as! FotoProdutoLojaCollectionViewItem
produtoLoja?.fotos[indexPath.item].foto?.getDataInBackground(block: {
(data: Data?, error: Error?) -> Void in
if error == nil {
fotosProdutoLojaCollectionViewItem.fotoProdutoLojaImageView.image = NSImage(data: data!)
}
})
if produtoLoja!.fotos[indexPath.item].imagemCapa {
fotosProdutoLojaCollectionViewItem.fotoCapaImageView.isHidden = false
}else {
fotosProdutoLojaCollectionViewItem.fotoCapaImageView.isHidden = true
}
return item
}
override func viewDidLoad() {
super.viewDidLoad()
fotosProdutoLojaCollectionView.delegate = self
fotosProdutoLojaCollectionView.dataSource = self
fotosProdutoLojaCollectionView.registerForDraggedTypes([NSPasteboard.PasteboardType(kUTTypeData as String)])
fotosProdutoLojaCollectionView.setDraggingSourceOperationMask(.move, forLocal: true)
}
Here is the pasteboardWriterForItemAt indexPath. I have tried all the commented lines.
func collectionView(_ collectionView: NSCollectionView, pasteboardWriterForItemAt indexPath: IndexPath) -> NSPasteboardWriting? {
let pb = NSPasteboardItem()
var data: Data?
do {
try data = produtoLoja?.fotos[indexPath.item].foto?.getData()
} catch {
}
pb.setData(data!, forType: NSPasteboard.PasteboardType.string)
return pb
//return NSPasteboardItem()
//return data as? NSPasteboardWriting
}
And here is the writeItemsAt indexPaths.
func collectionView(_ collectionView: NSCollectionView, writeItemsAt indexPaths: Set<IndexPath>, to pasteboard: NSPasteboard) -> Bool {
return true
}

Answer 1

A lot of methods were wrong. Here is the corrected code (just the parts related to the collection view delegate and data source to drag and drop items):
ViewDidLoad
var indiceItensMovidosDrag: Set<IndexPath> = []
override func viewDidLoad() {
super.viewDidLoad()
fotosProdutoLojaCollectionView.delegate = self
fotosProdutoLojaCollectionView.dataSource = self
fotosProdutoLojaCollectionView.registerForDraggedTypes([NSPasteboard.PasteboardType(kUTTypeItem as String)])
fotosProdutoLojaCollectionView.setDraggingSourceOperationMask(.move, forLocal: true)
if produtoLoja == nil {
produtoLoja = ProdutoLoja()
}
}
Now the delegate and data source methods methods
func numberOfSections(in collectionView: NSCollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
return produtoLoja!.fotos.count
}
func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
var item = NSCollectionViewItem()
item = collectionView.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "FotoProdutoLojaCollectionViewItem"), for: indexPath)
let fotosProdutoLojaCollectionViewItem = item as! FotoProdutoLojaCollectionViewItem
produtoLoja?.fotos[indexPath.item].foto?.getDataInBackground(block: {
(data: Data?, error: Error?) -> Void in
if error == nil {
fotosProdutoLojaCollectionViewItem.fotoProdutoLojaImageView.image = NSImage(data: data!)
}
})
if produtoLoja!.fotos[indexPath.item].imagemCapa {
fotosProdutoLojaCollectionViewItem.fotoCapaImageView.isHidden = false
}else {
fotosProdutoLojaCollectionViewItem.fotoCapaImageView.isHidden = true
}
return item
}
func collectionView(_ collectionView: NSCollectionView, canDragItemsAt indexPaths: Set<IndexPath>, with event: NSEvent) -> Bool {
return true
}
func collectionView(_ collectionView: NSCollectionView, pasteboardWriterForItemAt indexPath: IndexPath) -> NSPasteboardWriting? {
let retorno = NSPasteboardItem()
var data: Data?
do {
try data = produtoLoja?.fotos[indexPath.item].foto?.getData()
} catch {
}
retorno.setData(data!, forType: NSPasteboard.PasteboardType(kUTTypeItem as String))
return retorno
}
func collectionView(_ collectionView: NSCollectionView, draggingSession session: NSDraggingSession, willBeginAt screenPoint: NSPoint, forItemsAt indexPaths: Set<IndexPath>) {
indiceItensMovidosDrag = indexPaths
}
func collectionView(_ collectionView: NSCollectionView, draggingSession session: NSDraggingSession, endedAt screenPoint: NSPoint, dragOperation operation: NSDragOperation) {
indiceItensMovidosDrag = []
}
func collectionView(_ collectionView: NSCollectionView, validateDrop draggingInfo: NSDraggingInfo, proposedIndexPath proposedDropIndexPath: AutoreleasingUnsafeMutablePointer<NSIndexPath>, dropOperation proposedDropOperation: UnsafeMutablePointer<NSCollectionView.DropOperation>) -> NSDragOperation {
if proposedDropOperation.pointee == NSCollectionView.DropOperation.on {
proposedDropOperation.pointee = NSCollectionView.DropOperation.before
}
return NSDragOperation.move
}
func collectionView(_ collectionView: NSCollectionView, acceptDrop draggingInfo: NSDraggingInfo, indexPath: IndexPath, dropOperation: NSCollectionView.DropOperation) -> Bool {
var retorno = true
if indiceItensMovidosDrag.count == 1 {
for indice in indiceItensMovidosDrag {
collectionView.animator().moveItem(at: indice, to: (indexPath.item <= indice.item) ? indexPath : (IndexPath(item: indexPath.item - 1, section: 0)))
}
} else {
mostrarErro(mensagem: "Erro", informativo: "Só é possível mover uma imagem por vez")
retorno = false
}
//fotosProdutoLojaCollectionView.reloadData()
return retorno
}