问题
I have a macOS application that contains a tab bar design (ie: Tweetbot). There are 4 tabs that are linked to 4 different view controllers. The initial view controller (view one) contains a NSCollectionView which displays 3 cells horizontally.
This all works fine, however when I switch to another view controller and then come back to the initial view controller, the order of the collection view changes for no reason. I am not making ANY changes to the data source (which is a NSMutableArray) and I am not adding/deleting any cells, nor am I calling reloadData. I don't understand why the order of the collection view cells keep changing.
I have done some testing and can confirm that the order of the data in my data source, does NOT change at all. So it makes no sense for the collection view, to just change the order of the cells.
Another weird issue I have noticed, is that if I limit the collection view to 2 cells, this issue does not occur. This makes me wonder whether or not, the issue is down to some sort of NSCollectionView caching method that runs in the background? Perhaps when the collection view recycles a cell, it uses the incorrect data??
I have tried lots of different solutions, nothing seems to work. Does anyone have any ideas of what I can test/try out, in order to find out what's wrong?
Alternative idea
I could use NSTableView instead, because it supports multiple columns (unlike UITableView). So I could just make an NSTableView with 3 columns. Would this approach be any worse performance wise, than a NSCollectionView (especially if I wanted to add lots of cells?).
Thanks for your time, Dan.
回答1:
I couldn't find out what was wrong with the collection view. So I ended up using a NSTableView with multiple columns (instead of collection view rows). I set each column to have one row (index 0), which makes the table view look exactly like the collection view I was working with.
Performance wise the table view seems to be a lot better too. Even with hundreds of columns, it's still nice and smooth when scrolling/interacting.
来源：https://stackoverflow.com/questions/46691310/nscollectionview-cell-order-changes-on-view-change