UITabBarController在故事板上方添加新的UIViewController（Swift）

Question

我有一個連接到4個視圖控制器的UITabBarController故事板文件，我想以編程方式添加數字5。在Objective-C中，我的做法如下：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 

    NSArray *tabs = self.viewControllers; 

    //set tab controllers 
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:(@"Settings_Storyboard_iPad") bundle:nil]; 
    AddFolderViewController *vc = [storyboard instantiateInitialViewController]; 
    self.viewControllers = [NSArray arrayWithObjects:[tabs objectAtIndex:0], [tabs objectAtIndex:1], [tabs objectAtIndex:2], [tabs objectAtIndex:3], vc, nil]; 
} 

在UITabBarController的子類中。然而在Swift中，我似乎無法做到這一點。它不允許我訪問製表符的索引，或者追加controller。

Answer 1

override func viewDidLoad() { 
     super.viewDidLoad() 
    var viewControllers: [UIViewController] = self.viewControllers as! [UIViewController]; 

    let storyboard : UIStoryboard = UIStoryboard(name:"Main", bundle: nil) 
    let thirdVC : ThirdViewController = storyboard.instantiateViewControllerWithIdentifier("ThirdVC") as! ThirdViewController 


    let icon1 = UITabBarItem(title: "Third", image:UIImage(named: "image.png"), selectedImage:UIImage(named: "otherImage.png")) 
    thirdVC.tabBarItem = icon1 
    viewControllers.append(thirdVC) 
    self.viewControllers = viewControllers 

}