Invalidates the current layout using the information in the provided context object.
- iOS 7.0+
- tvOS 9.0+
The context object indicating which parts of the layout to refresh.
The default implementation of this method optimizes the layout process using the base properties of the
UICollection class. If you define a custom context object for your layout, override this method and apply any custom properties of the context object to your layout computations.
If you override this method, you must call
super at some point in your implementation.