storyboard切换程序进入页面

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    if([userDefaults objectForKey:@"autoLogIn"] != nil && [userDefaults objectForKey:@"rand_code"] != nil) {
        UIStoryboard *board = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
        //获取故事板中某个View
        UIViewController *next = [board instantiateViewControllerWithIdentifier:@"mainTabBar"];
        [self.window setRootViewController:next];
        [self.window makeKeyAndVisible];
    }else{
        UIStoryboard *board = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
        //获取故事板中某个View
        UIViewController *next = [board instantiateViewControllerWithIdentifier:@"mainTabBar"];
        [self.window setRootViewController:next];
        [self.window makeKeyAndVisible];
    }
    return YES;
}