build method Null safety
- BuildContext context
Called by the Router to obtain the widget tree that represents the current state.
This is called whenever the Futures returned by setInitialRoutePath, setNewRoutePath, or setRestoredRoutePath complete as well as when this notifies its clients (see the Listenable interface, which this interface includes). In addition, it may be called at other times. It is important, therefore, that the methods above do not update the state that the build method uses before they complete their respective futures.
Typically this method returns a suitably-configured Navigator. If you do plan to create a navigator, consider using the PopNavigatorRouterDelegateMixin. If state restoration is enabled for the Router using this delegate, consider providing a non-null Navigator.restorationScopeId to the Navigator returned by this method.
This method must not return null.
context is the Router's build context.
Widget build(BuildContext context);