CODEWITHSUNDEEP
swiftmacosexceptionnscollectionviewnscollectionviewitem
Rohan
Rohan

Reputation: 551

Assertion failure when using NSCollectionView

I am currently developing an OS X application with Swift. I am trying to use an NSCollectionView in my main view, and so I have added an NSCollectionView object to my .xib file. I haven't changed anything in regards to that other than linking the data source and delegate to the File's Owner.

This is the code I have written to implement the NSCollectionViewDataSource protocol:

/// MARK: - NSCollectionViewDataSource
extension MainViewController: NSCollectionViewDataSource {
  func collectionView(collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
    return 10
  }

  func collectionView(collectionView: NSCollectionView, itemForRepresentedObjectAtIndexPath indexPath: NSIndexPath) -> NSCollectionViewItem {
    let itemView = collectionView.makeItemWithIdentifier("fileItem", forIndexPath: indexPath)
    itemView.textField!.stringValue = "TEST"

    return itemView
  }

}

Now, when I run my code, I am getting an uncaught exception, and the application crashes, and I am not sure why. Here is part of the stack trace that I think is useful:

2016-04-02 18:58:02.768 Pilot[5442:679789] *** Assertion failure in -[NSCollectionView setItemPrototype:], /Library/Caches/com.apple.xbs/Sources/AppKit/AppKit-1404.46/Binding.subproj/NSCollectionView.m:1286
2016-04-02 18:58:02.971 Pilot[5442:679789] An uncaught exception was raised
2016-04-02 18:58:02.971 Pilot[5442:679789] Use -registerNib:forItemWithIdentifier: and -registerClass:forItemWithIdentifier: with new CollectionViews

Any help would be greatly appreciated.

Upvotes: 1

Views: 1494

Answers (1)

Ky -
Ky -

Reputation: 32163

You have to register custom views like this:

collectionView.register(MyFileCollectionViewItem.self, forItemWithIdentifier: "fileItem")

before loading any items into the collection view (I recommend in the same block it's created, or in viewDidLoad() of its controller).

Upvotes: 1

Related Questions