UISearchBar not responding

Perhaps the problem is that your controller or view (I know without code) did not add the protocol correctly.

Anyway, this is an example of using UISearchController:

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate, UISearchControllerDelegate, UISearchBarDelegate, UISearchResultsUpdating>

@property (nonatomic, weak) IBOutlet UITableView * tableView;
@property (nonatomic, strong) UISearchController * searchController;
@property (nonatomic, strong) NSMutableArray * allItems;
@property (nonatomic, strong) NSMutableArray * filteredItems;
@property (nonatomic, weak) NSArray * displayedItems;

@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize tableView;
@synthesize searchController;
@synthesize allItems;
@synthesize displayedItems;
@synthesize filteredItems;

- (void)viewDidLoad {
     [super viewDidLoad];

     // Create a list

     self.allItems = [[NSMutableArray alloc] init];
     [self.allItems addObject:@"One"];
     [self.allItems addObject:@"Two"];
     [self.allItems addObject:@"Three"];


     // Create a list to hold search results (filtered list)
    self.filteredItems = [[NSMutableArray alloc] init];

    // Initially display the full list.  This variable will toggle between the full and the filtered lists.
    self.displayedItems = self.allItems;

    // Here where we create our UISearchController

    self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
    self.searchController.searchResultsUpdater = self;
    self.searchController.searchBar.delegate = self;

    [self.searchController.searchBar sizeToFit];

    // Add the UISearchBar to the top header of the table view
    self.tableView.tableHeaderView = self.searchController.searchBar;

    // 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)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (NSInteger)tableView:(UITableView *)aTableView numberOfRowsInSection:(NSInteger)section {
    return [self.displayedItems count];
}

- (UITableViewCell *)tableView:(UITableView *)aTableView cellForRowAtIndexPath:(NSIndexPath *)anIndexPath {

    UITableViewCell * cell = [aTableView dequeueReusableCellWithIdentifier:@"FruitCell"];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] init];
    }
    cell.textLabel.text = [self.displayedItems objectAtIndex:anIndexPath.row];
    return cell;
}

// When the user types in the search bar, this method gets called.
- (void)updateSearchResultsForSearchController:(UISearchController *)aSearchController {
    NSLog(@"updateSearchResultsForSearchController");

    NSString *searchString = aSearchController.searchBar.text;
    NSLog(@"searchString=%@", searchString);

    // Check if the user cancelled or deleted the search term so we can display the full list instead.
    if (![searchString isEqualToString:@""]) {
        [self.filteredItems removeAllObjects];
        for (NSString *str in self.allItems) {
            if ([searchString isEqualToString:@""] || [str localizedCaseInsensitiveContainsString:searchString] == YES) {
                NSLog(@"str=%@", str);
                [self.filteredItems addObject:str];
            }
        }
        self.displayedItems = self.filteredItems;
    }
    else {
        self.displayedItems = self.allItems;
    }
    [self.tableView reloadData];
}


    @end