Why does NSCollectionView.makeItem sometimes crash with EXC_BAD_ACCESS?

Question

For some reason, my app just started doing this after months of not doing so. This popped up after a seemingly-unrelated use of OperationQueue (I always use main, so it's done on Thread 1).

As you can see, I call the exact same function 6 times in a row, and only on the 4th time does it fail. I see no pattern...

Answer 1

I haven't done very extensive digging or testing, but it seems a block like this was the culprit:

collectionView.performBatchUpdates({
    collectionView.reloadItems()
}, completionHandler: { [weak self] _ in
    // cleanup
})

Seems the collection view doesn't like doing much more than insert+remove inside the batch update context. Changing it to this seems to have cured the crash:

collectionView.reloadItems()
// cleanup