TabBar選択するとModalView開くやつ

gistfile1.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    UIViewController *viewController1, *viewController2;
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        viewController1 = [[FirstViewController alloc] initWithNibName:@"FirstViewController_iPhone" bundle:nil];
        viewController2 = [[SecondViewController alloc] initWithNibName:@"SecondViewController_iPhone" bundle:nil];
    } else {
        viewController1 = [[FirstViewController alloc] initWithNibName:@"FirstViewController_iPad" bundle:nil];
        viewController2 = [[SecondViewController alloc] initWithNibName:@"SecondViewController_iPad" bundle:nil];
    }
    CenterViewController *centerViewController = [[CenterViewController alloc] initWithNibName:@"CenterViewController" bundle:nil];

    self.tabBarController = [[UITabBarController alloc] init];
    self.tabBarController.delegate = self;
    self.tabBarController.viewControllers = @[viewController1, centerViewController, viewController2];
    self.window.rootViewController = self.tabBarController;
    [self.window makeKeyAndVisible];
    return YES;
}

// 中略

#pragma mark UITabBarControllerDelegate method
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
    if ([viewController isKindOfClass:[CenterViewController class]]) {
        UIViewController *vc = [[UIViewController alloc] init];
        vc.view.backgroundColor = [UIColor redColor];
        [viewController presentViewController:vc animated:YES completion:nil];
        return NO;
    }
    return YES;
}

これの前に self.tabBarController.delegate = self; が必要です