NSCollectionViewTransitionLayout API is incomplete on MacOS

Number:rdar://FB9671572 Date Originated:02/10/2021
Status:Open Resolved:
Product:AppKit Product Version:11.5.2
Classification:Incorrect/Unexpected Behavior Reproducible:YES
MacOS 10.11 introduced NSCollectionViewTransitionLayout, and the NSCollectionViewDelegate method collectionView(_:transitionLayoutForOldLayout:newLayout:), but these are documented as follows:

“In macOS 10.11, collection views do not provide built-in support for driving layout transitions.” and for the delegate method “In OS X 10.11, this method is never called by the collection view.”

It looks like these never actually got implemented, and current MacOS still seems to be missing the equivalent of UICollectionView’s startInteractiveTransition(to:completion:) method.

Please can we have the rest of the layout transition API on MacOS, so that we can easily perform gesture driven transitions.


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