Swift iOS - 如何使用NavigationController彈出到不同的SegmentControl索引

Question

           //Index=0  //contains buttonToSwitchTab to pop to TabOneVC 
          TabZeroNavCntrlr ----TabZeroVC --- TabChangeVC 
      //segmntCntrl /
NavCntlr--ContainerView--- 
          \      //Index=1 
          TabOneNavCntrlr ---- TabOneVC 

我有一個NavController已連接ContainerView。在containerView裏面有一個segmentControl。 containerView有兩個導航控制器連接到它，每個導致他們自己的子控制器：TabZeroVC和TabOneVC。最初顯示的第一個視圖是TabZeroVC（selectedSegmentIndex = 0）。裏面有一個按鈕，導致TabChangeVC裏面有一個buttonToSwitchTab。按下那個按鈕我想要pop到TabOneVC。

我用我的導航控制器使開關，但上線tabOneVC.segmentedControl.selectedSegmentIndex = 1下方嘗試這種代碼，我得到一個崩潰：意外發現零而展開的可選值

我上放一個破發點它和containerVC被初始化，但它的3個屬性segmentedControl,tabZeroVC和tabOneVC都是零。由於segmentedControl是無這就是發生崩潰的地方。

class TabChangeVC: UIViewController{ 

@IBAction func buttonToSwitchTab(sender: UIButton){ 

    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil) 
    let containerVC = mainStoryboard.instantiateViewControllerWithIdentifier("ContainerViewController") as! ContainerViewController 
    containerVC.segmentedControl.selectedSegmentIndex = 1 //crash happens here 
    self.navigationController?.popToViewController(containerVC, animated: true) 
    } 
} 

ContainerView：

class ContainerViewController: UIViewController{ 
    @IBOutlet weak var segmentedControl: UISegmentedControl! 
    @IBOutlet weak var tabZeroVC: UIView! 
    @IBOutlet weak var tabOneVC: UIView! 

... 
} 

TabOneVC是selectedSegmentIndex = 1

我的問題是我怎麼彈出來TabOneVC從TabChangeVC，更重要的原因是containerVC的segmentedControl來了爲零？

Answer 1

我不知道爲什麼segmentedControl快到了作爲零但我能pop到tabOneVC使用NSNotificationCenter。我創建）名爲tabSwitch（一FUNC與我想表現的段，然後我增加了一個listener的ContainerViewController的viewDidLoad內：

class ContainerViewController: UIViewController{ 
    @IBOutlet weak var segmentedControl: UISegmentedControl! 
    @IBOutlet weak var tabZeroVC: UIView! 
    @IBOutlet weak var tabOneVC: UIView! 

override func viewDidLoad() { 
    super.viewDidLoad() 

    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(tabSwitch), name: "tabSwitch", object: nil) 
    } 

func tabSwitch(){ 

    self.segmentedControl.selectedSegmentIndex = 1 
    self.tabZeroVC.hidden = true 
    self.tabOneVC.hidden = false 
    } 
} 

的TabChangeVC我在裏面加了notifier來觸發它，navigationController?.popToRootViewControllerAnimated(true)到我們回到root VC：

class TabChangeVC: UIViewController{ 

@IBAction func buttonToSwitchTab(sender: UIButton){ 

    NSNotificationCenter.defaultCenter().postNotificationName("tabSwitch", object: nil) 
    self.navigationController?.popToRootViewControllerAnimated(true) 
    } 
} 

Answer 2

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate 
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil 
let tabOneVC = mainStoryboard.instantiateViewControllerWithIdentifier("TabOneNavigationController") //TabOneNavCntrlr identifire  
tabOneVC.segmentedControl.selectedSegmentIndex = 1 
appDelegate.window!.rootViewController = tabOneVC