1.首先定义属性
@property (nonatomic, retain) UISearchDisplayController *searchDisplayController;
2.创建一个UISearchBar
UISearchBar *search = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 40)];
    [search setPlaceholder:@"搜索"];
    [search setAutocapitalizationType:UITextAutocapitalizationTypeNone];
    [search setAutocorrectionType:UITextAutocorrectionTypeNo];
3.将UISearchBar加入UITableHeaderView
self.tableView.tableHeaderView = search;
4.最后将UISearchBar加入UiSearchDisplaycontroller
self.searchDisplayController = [[UISearchDisplayController alloc] initWithSearchBar:search contentsController:self];
5.设置代理
self.searchDisplayController.delegate = self;
self.searchDisplayController.searchResultsDataSource = self;
self.searchDisplayController.searchResultsDelegate = self;