從一個UINavigationController接口到另一個UINavigationController（Swift iOS 9，xcode 7）

Question

作爲iOS開發的新手，我很好奇什麼可能是最好的方法，我需要從初始的UINavigationController分支到另一個UINavigationController取決於某些條件。例如，當用戶第一次啓動應用程序時，我想呈現「創建帳戶」系列屏幕（我需要有多個屏幕）。但是，如果它們已經被激活，我希望能夠分支到另一個UINavigationController，它的根視圖控制器就是密碼輸入屏幕，後面還有更多的屏幕。人們如何做這種事情？我試着在主導航控制器的viewDidLoad（）方法中放入代碼，然後在檢查條件（例如是否存在密碼）後調用performSegueWithIdentifier，但是當我繼續時，我得到一個空白屏幕，因爲它顯示另一個UINavigationController而不是根控制器它指向。我究竟做錯了什麼？我真的沒有任何代碼可以顯示，只是要求一個例子，或者如果有更好的方法來做這種事情。

我不應該能夠做到這樣嗎？

Answer 1

在應用程序啓動，檢查帳戶已創建/登錄，如果是這樣，創建首頁導航控制器，並將其設置爲rootViewController。如果沒有，則創建CreateAccount導航控制器並將其設置爲rootViewController。

在帳戶創建流程的最後，你可以出示首頁導航控制器上CreateAcccount導航控制器的頂模態。這不是什麼大問題，因爲在下次發佈時，您將僅實例化主頁導航控制器。

這就是我所說的：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    // ... 
    UIViewController *rootController = nil; 
    BOOL showCreateAccount = NO; // this should come from some storage e.g. NSUserDefaults 
    if(showCreateAccount == NO) 
    { 
     rootController = homeController; // create homeController 
    } 
    else 
    { 
     rootController = createAccountController; // create createAccountController 
    } 

    NSAssert(rootController, @"no user interface, what is this? a web service??"); 
    self.window.rootViewController = rootController; 
    [self.window makeKeyAndVisible]; 
    return YES; 
} 

如果你真的想從視圖層次結構中刪除的createAccount控制器和帶有首頁控制器替換它，你應該創建一個自定義SEGUE。 This Stackoverflow Question應該讓你開始。

Answer 2

你可以在一個VC中完成所有工作。爲例如創建手勢識別器。向上滑動&向下滑動，然後對每個單獨設置使用開關盒。您可以輕鬆地添加一個計數器+1以向上滑動，向下滑動則可以添加-1，這樣您甚至可以返回到手勢識別器中。

您隨後進行更改的方式是由例如。在每種情況下

switch swipeCounter { 
     case 1: 
     label.text = "do this" 
     funcForSomething() 
     default: 
     label.text = "do that" 
     funcForSomethingElse() 
    } 

這裏給你的標籤新的文本是一個更完整的例子，你可能能夠使用（斯威夫特2）

通知我宣佈這則用來檢查VAR upSwipes我在那裏的順序。查看我的屏幕截圖，瞭解「情況0」的外觀。

var upSwipes = 0 

    override func viewDidLoad() { 
    super.viewDidLoad() 

    self.openingText.alpha = 0.0 
    self.swipeUp.alpha = 0.0 

    let swipeRight = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:") 
    swipeRight.direction = UISwipeGestureRecognizerDirection.Right 
    self.view.addGestureRecognizer(swipeRight) 

    let swipeUp = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:") 
    swipeUp.direction = UISwipeGestureRecognizerDirection.Up 
    self.view.addGestureRecognizer(swipeUp) 

    let swipeDown = UISwipeGestureRecognizer(target: self, action: "respondToSwipeGesture:") 
    swipeDown.direction = UISwipeGestureRecognizerDirection.Down 
    self.view.addGestureRecognizer(swipeDown) 

    } 


func respondToSwipeGesture(gesture: UIGestureRecognizer) { 

    if let swipeGesture = gesture as? UISwipeGestureRecognizer { 


     switch swipeGesture.direction { 
     case UISwipeGestureRecognizerDirection.Down: 
     print("minus 1") 
     if upSwipes != 0 { upSwipes = upSwipes - 1} 
     case UISwipeGestureRecognizerDirection.Up: 
     print("plus 1") 
       upSwipes = upSwipes + 1 
     default: print("other direction") 
     } 

     switch upSwipes { 
     case 0: 
      self.openingText.alpha = 0.0 
      self.swipeUp.alpha = 0.0 
      self.openingText.text = "Swipe up, not down you silly " 
      self.openingText.alpha = 1.0 
      self.swipeUp.alpha = 1.0 
     case 1: 
      self.openingText.alpha = 0.0 
      self.swipeUp.alpha = 0.0 
      self.openingText.text = "Case specific text. Please swipe up again." 
      self.openingText.alpha = 1.0 
      self.swipeUp.alpha = 1.0 
      // Sequence to tell specifically why you need GPS permission and that in the next frame you will ask for it   
     case 2: 
      self.openingText.alpha = 0.0 
      self.swipeUp.alpha = 0.0 
     //   initialAuthorization() // Your func to ask for GPS permission 
      // Sequence to ask eg. GPS use permission 
     case 3: 
      self.openingText.alpha = 0.0 
      self.swipeUp.alpha = 0.0 
      self.openingText.text = "Case specific text. Please swipe up again." 
      self.openingText.alpha = 1.0 
      self.swipeUp.alpha = 1.0 
      // Sequence to eg. ask name 
     case 4: 
      self.openingText.alpha = 0.0 
      self.swipeUp.alpha = 0.0 
      self.openingText.text = "Case specific text. Please swipe up again." 
      self.openingText.alpha = 1.0 
      self.swipeUp.alpha = 1.0 
      // Sequence to eg. send verification email 
     default: 
      self.openingText.alpha = 0.0 
      self.swipeUp.alpha = 0.0 

      let vc = storyboard?.instantiateViewControllerWithIdentifier("initilizing-done") as! InitializingDoneViewController 
      presentViewController(vc, animated: true, completion: nil) 
      // Then finally you might choose to go to other view controller. You need file (Cocoa class) with the same name InitializingDoneViewController.swift and VC whose specification will then be used for this VC that is modally shown herein. 
     } 
    } 

Answer 3

這是我得到了它在斯威夫特工作：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { 
    // Override point for customization after application launch. 

    let activated = false || false 
    let storyboard = UIStoryboard(name: "Main", bundle: nil) 
    let navController = activated ? "createAccount" : "enterPassword" 

    let navViewController = storyboard.instantiateViewControllerWithIdentifier(navController) as! UINavigationController 

    window?.rootViewController = navViewController 
    window?.makeKeyAndVisible() 

    return true 
}