UISearchViewController:Attempting to load the view of a view controller while it is deallocating is not allowed and may result in undefined behavior ()

UISearchViewController bug:

在工程中使用UISearchViewController ， 当跳出UISearchViewController 的容器视图控制器时，控制台输出以下警告信息：

Attempting to load the view of a view controller while it is deallocating is not allowed and may result in undefined behavior ()

解决办法：
方式一：

• (void)viewDidLoad {
  [super viewDidLoad];
  }

方式二：

• (void)dealloc {
  // 解决UISearchController bug
  [self.searchController loadViewIfNeeded];
  UIView *view = self.searchController.view;
  }