[ASCollectionNode] More info on changes in #797

[flovouin]

Hi guys,

I recently posted an issue about a crash caused by #797 that has since been solved. However this same PR also had an undesirable effect on some of my ASCollectionNode layout and behaviour.

The original problem I had solved a long time ago was: "How to scroll to a given cell (or page, with isPagingEnabled) as soon as the data has been loaded?"
I remember asking this question on Slack and experimenting with several solutions including using reloadData, waitUntilAllUpdatesAreProcessed, etc. Eventually what was working 100% for me was something along the lines of:

override func interfaceStateDidChange(_ newState: ASInterfaceState, from oldState: ASInterfaceState) {
    super.interfaceStateDidChange(newState, from: oldState)

    if !oldState.contains(.inHierarchy), newState.contains(.inHierarchy), let index = self.preLoadIndex {
        self.preLoadIndex = nil
        self.collectionNode.scrollToItem(at: IndexPath(item: index, section: 0), at: [], animated: animated)
    }
}

This was until #797, which introduces this change. Now some of my collection nodes no longer scroll to the correct index. Reverting this single line solves the problem for me, but I had two questions:

• First of all, are there any other ways of reliably scrolling to a given cell as soon as the collection loads and is displayed? This might avoid finding a workaround/fix altogether.
• Out of curiosity (and interest!) why was this change made? If the collection node is not part of a range managed hierarchy, why shouldn't the initial data load be triggered at this moment?

Maybe @appleguy could help me figure this out? 😊

Cheers,