当UISearchController呈现时未调用的UIViewControllerPreviewingDelegate方法

Question

当没有呈现searchController时,3d touch按预期工作并调用委托方法.但是当searchController处于活动状态时不会调用.

UISearchController的创建看起来像这样

let searchController = UISearchController(searchResultsController: nil) 
searchController.searchResultsUpdater = self
searchController.delegate = self
searchController.hidesNavigationBarDuringPresentation = false
searchController.dimsBackgroundDuringPresentation = false