Swift: NSCollectionViewItem not showing in NSViewController - swift

Question

I am building an app with NSCollectionView and behaviour of NSCollectionView is so strange, sometimes it makes cell's visible and sometimes are not.
#IBOutlet weak var resourceCollectionView: NSCollectionView!
private func prepareCollectionView() {
let flowLayoutForEvent = NSCollectionViewFlowLayout()
flowLayoutForEvent.scrollDirection = .vertical
flowLayoutForEvent.minimumInteritemSpacing = 100
resourceCollectionView.collectionViewLayout = flowLayoutForEvent
resourceCollectionView.delegate = self
resourceCollectionView.dataSource = self
resourceCollectionView.isSelectable = true
resourceCollectionView.backgroundColors = [.clear]
resourceCollectionView.register(SimpleCell.self, forItemWithIdentifier: NSUserInterfaceItemIdentifier(rawValue: "SimpleCell"))
}
Then applied the function
public override func viewDidLoad() {
super.viewDidLoad()
prepareCollectionView()
}
Here is extension function for NSCollectionView
extension DashboardController : NSCollectionViewDelegateFlowLayout, NSCollectionViewDataSource {
// 1
public func numberOfSections(in collectionView: NSCollectionView) -> Int {
return 1
}
// 2
public func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
// 3
public func collectionView(_ itemForRepresentedObjectAtcollectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
let cell = resourceCollectionView.makeItem(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "SimpleCell"), for: indexPath) as! SimpleCell
return cell
}
public func collectionView(_ collectionView: NSCollectionView, didSelectItemsAt indexPaths: Set<IndexPath>) {
print("selected item > ", indexPaths )
}
public func collectionView(_ collectionView: NSCollectionView, layout collectionViewLayout: NSCollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> NSSize {
return NSSize(width: 10 , height:10)
}
}
Here is programmatically cell for NSCollectionView
class SimpleCell: NSCollectionViewItem {
private var containerView: NSView!
private var containBox: NSBox = {
var box = NSBox()
box.boxType = .custom
box.fillColor = NSColor.purple
box.translatesAutoresizingMaskIntoConstraints = false
return box
}()
override func loadView() {
containerView = NSView()
self.view = containerView
containerView.bounds = self.view.bounds
containerView.addSubview(containBox)
containBox.topAnchor.constraint(equalTo: containerView.topAnchor).isActive = true
containBox.leftAnchor.constraint(equalTo: containerView.leftAnchor).isActive = true
containBox.bottomAnchor.constraint(equalTo: containerView.bottomAnchor).isActive = true
containBox.rightAnchor.constraint(equalTo: containerView.rightAnchor).isActive = true
}
}
resourceCollectionView not showing the cells and there is a strange behaviour such as when I add a line resourceCollectionView.reloadData() it shows up and then hides all cells automatically.
What is the missing points for the situation?
Thanks in advance
Edit:
I've solved my problem, when I show another NSViewController I used
self.view = anotherViewController.view
then no functions of NSCollectionView is triggered.
Then I changed it to
self.view.window?.contentViewController = anotherViewController
Then it worked.

Answer 1

I've solved my problem, when I show another NSViewController I used
self.view = anotherViewController.view
then no functions of NSCollectionView is triggered.
Then I changed it to
self.view.window?.contentViewController = anotherViewController
It solved my problem.