invalidateSupplementaryElements(ofKind:at:)
Marks the specified supplementary views as invalid so that their layout information can be updated.
Declaration
func invalidateSupplementaryElements(ofKind elementKind: NSCollectionView.SupplementaryElementKind, at indexPaths: Set<IndexPath>)Parameters
- elementKind:
A string that identifies the type of the supplementary views. This parameter must not be
nilor an empty string. - indexPaths:
A set of Nsindexpath objects. Each index path contains the section in which the supplementary view appears.
Discussion
Call this method when you want the layout object to recompute attributes for one or more supplementary views. All of the views must be of the type specified by the elementKind parameter. The method adds the views you specify to the invalidatedSupplementaryIndexPaths property. You can call this method more than once for the specified elementKind value.