How to disable implicit decoration view animation in UICollectionView

Issue #569

From documentation https://developer.apple.com/documentation/uikit/uicollectionviewlayout/1617726-initiallayoutattributesforappear

This method is called after the prepare(forCollectionViewUpdates:) method and before the finalizeCollectionViewUpdates() method for any decoration views that are about to be inserted. Your implementation should return the layout information that describes the initial position and state of the view. The collection view uses this information as the starting point for any animations. (The end point of the animation is the view’s new location in the collection view.) If you return nil, the layout object uses the item’s final attributes for both the start and end points of the animation.

The default implementation of this method returns nil.

Although the doc says “The default implementation of this method returns nil”, calling super.initialLayoutAttributesForAppearingDecorationElement gives somehow implicit animation. The workaround is to explicitly return nil

func initialLayoutAttributesForAppearingDecorationElement(ofKind elementKind: String, at decorationIndexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
    return nil
}

func finalLayoutAttributesForDisappearingDecorationElement(ofKind elementKind: String, at decorationIndexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
    return nil
}

Decoration seems to be removed when all items are removed. Workaround is to check and only add decoration when there is preferred data or cell