如何在iOS11中更改UISearchController.searchBar.height？

Question

navigationBar.frame.size.height是44.0f;

但是UISearchController.searchBar.height是56.0f;

[self.view addSubview:self.searchController.searchBar];

如何在iOS11中更改UISearchController.searchBar.height？ searchBar.frame.size.height = 35是没用的