问激活时UISearchController搜索栏与第一个单元格重叠

EN

self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
self.searchController.searchResultsUpdater = self;
self.tableView.tableHeaderView = self.searchController.searchBar;
[self.searchController.searchBar sizeToFit];

// we want to be the delegate for our filtered table so didSelectRowAtIndexPath is called for both tables
self.searchController.delegate = self;
self.searchController.dimsBackgroundDuringPresentation = NO; // default is YES
self.searchController.searchBar.delegate = self; // so we can monitor text changes + others

// Search is now just presenting a view controller. As such, the normal view controller
// presentation semantics apply. Namely, that presentation will walk up the view controller
// hierarchy until it finds the root view controller or one that defines a presentation context.
//
self.definesPresentationContext = YES;  // know where you want UISearchController to be displayed

// Hides search bar initially. When the user pulls down on the list, the search bar is revealed.
[self.tableView setContentOffset:CGPointMake(0, self.searchController.searchBar.frame.size.height)];

-(void)willPresentSearchController:(UISearchController *)searchController{

     [self.contactsTableView setContentInset:UIEdgeInsetsMake(20, 0, 0, 0)];
     [self.contactsTableView setContentOffset:CGPointMake(0.0f, -self.contactsTableView.contentInset.top) animated:YES];
 }

-(void)willDismissSearchController:(UISearchController *)searchController{

     [self.contactsTableView setContentInset:UIEdgeInsetsMake(0, 0, 0, 0)];
}

  self.tableView.contentInset = UIEdgeInsets(top: 20, left: 0, bottom: 0, right: 0)

  self.tableView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)