A Boolean that indicates whether all layout data should be marked as invalid.
- macOS 10.11+
The collection view sets this property in response to specific layout invalidation scenarios. For example, the collection view sets the property to
true when you change the current layout object, change the data source of the collection view, or call the
reload method and subsequently request a layout invalidation context.
When this property is set to
true, the layout object must throw away all previous layout information and recompute it.