Cannot select CollectionView item if the item integrates another CollectionView - ios

Question

My NSCollectionView item integrates another NSCollectionView. Everything works great but not when it comes to items selection in the first view.
When I set collectionView1.isSelectable = true, the didSelectItemsAt delegate is called only if I click somewhere else than the second (integrated) collectionView. To be clearer, if I click on a label, an image or a custom view: it works. As soon as I click on the second collection view, the delegate is not called.
Here is what I have tried so far:
Setting collectionView2.isSelectable = true to the second view.
That did not work.
I followed this tip. Curiously that did not work either. I got the same behaviour.
The only thing that works is to add a gesture recogniser on each integrated collection view. But this is so ugly...
I haven't tried on iOS yet with UICollectionView and cell selection, but I tend to think that the problem is the same.
EDIT:
So, if I click on the green label or everywhere on the blue part (which is the first collection view item), the didSelectItemsAt delegate is called correctly.
If I click on the orange NSView (with the second CollectionView inside), it's not called..
Heres is the simplified code of the first CollectionView:
class DashboardVC: NSViewController {
#IBOutlet weak var collectionView1: NSCollectionView!
override func viewDidLoad() {
super.viewDidLoad()
self.initViews()
}
fileprivate func initViews() {
let flowLayout = NSCollectionViewFlowLayout()
flowLayout.itemSize = NSSize(width: 400.0, height: 380.0)
flowLayout.sectionInset = NSEdgeInsets(top: 20.0, left: 20.0, bottom: 20.0, right: 20.0)
flowLayout.minimumInteritemSpacing = 20.0
flowLayout.minimumLineSpacing = 20.0
self.collectionView1.collectionViewLayout = flowLayout
self.collectionView1.isSelectable = true
self.collectionView1.dataSource = self
self.collectionView1.delegate = self
}
}
extension DashboardVC: NSCollectionViewDataSource {
func numberOfSections(in collectionView: NSCollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
func collectionView(_ itemForRepresentedObjectAtcollectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
let item = self.collectionView1.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "CollectionViewItem"), for: indexPath)
guard let collectionViewItem = item as? CollectionViewItem else { return item }
return collectionViewItem
}
}
extension DashboardVC: NSCollectionViewDelegate {
func collectionView(_ collectionView: NSCollectionView, didSelectItemsAt indexPaths: Set<IndexPath>) {
print("I can't make this work!")
}
}
And for the second collection view:
class TabularView: NSView {
lazy var collectionView2: NSCollectionView = {
let gridLayout = NSCollectionViewGridLayout()
gridLayout.maximumNumberOfColumns = self.numberOfColums
gridLayout.maximumNumberOfRows = self.numberOfRows
let collectionView = NSCollectionView(frame: .zero)
collectionView.collectionViewLayout = gridLayout
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.isSelectable = true //-> does not work :(
collectionView.dataSource = self
collectionView.delegate = self
return collectionView
}()
override init(frame frameRect: NSRect) {
super.init(frame: frameRect)
self.setup()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
self.setup()
}
private func setup() {
self.addSubview(self.collectionView)
NSLayoutConstraint.activate([
self.topAnchor.constraint(equalTo: self.collectionView.topAnchor),
self.bottomAnchor.constraint(equalTo: self.collectionView.bottomAnchor),
self.leadingAnchor.constraint(equalTo: self.collectionView.leadingAnchor),
self.trailingAnchor.constraint(equalTo: self.collectionView.trailingAnchor),
])
}
}
extension TabularView: NSCollectionViewDataSource {
func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
return self.numberOfRows * self.numberOfColums
}
func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
let item = collectionView.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "TabularCollectionViewItem"), for: indexPath)
guard let collectionViewItem = item as? TabularCollectionViewItem else { return item }
return collectionViewItem
}
}

Answer 1

If I'm understanding your problem correctly, you're trying to disable selection on a specific item in collectionView1 and instead have the user select the items of collectionView2 embedded in this cell.
Take a look at NSCollectionViewDelegate's collectionView(_:shouldSelectItemsAt:)
From the documentation:
Return Value
The set of NSIndexPath objects corresponding to the items that you want to be selected. If you do not want any items selected, return an empty set.