Objective-C: didSelectGame method not called - ios

Question

I was following this storyboard tutorial www.raywenderlich.com and got into the last steps.
After I finished with all the codes I ran the simulator and clicked the add button and select one of the game.
However it doesn't automatically return to the screen, and does not change the game to the one I have checked.
Here are my codes in gamepickerviewcontroller.m:
//
// GamePickerViewController.m
// TabBar_Demo_2
//
// Created by Haonan Chen on 16/7/1.
// Copyright © 2016年 fufjvnvnf. All rights reserved.
//
#import "GamePickerViewController.h"
#interface GamePickerViewController ()
#end
#implementation GamePickerViewController{
NSArray *_games;
NSUInteger _selectedIndex;
}
- (void)viewDidLoad
{
[super viewDidLoad];
_games = #[#"Angry Birds", #"Chess", #"Russian Roulette", #"Spin the Bottle", #"Texas Hold'em Poker", #"Tic-Tac-Toe"];
_selectedIndex = [_games indexOfObject:self.game];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return _games.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"GameCell"];
cell.textLabel.text = _games[indexPath.row];
if (indexPath.row == _selectedIndex) {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
} else {
cell.accessoryType = UITableViewCellAccessoryNone;
}
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
if (_selectedIndex != NSNotFound) {
UITableViewCell *cell = [tableView cellForRowAtIndexPath:
[NSIndexPath indexPathForRow:_selectedIndex inSection:0]];
cell.accessoryType = UITableViewCellAccessoryNone;
}
_selectedIndex = indexPath.row;
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
cell.accessoryType = UITableViewCellAccessoryCheckmark;
NSString *game = _games[indexPath.row];
[self.delegate gamePickerViewController:self didSelectGame:game];
}
#end