Storyboard - refer to ViewController in AppDelegate

Question

consider the following scenario  I have a storyboard-based app  I add a ViewController object to the storyboard  add the class files for this ViewController into the project and specify the name of the new class in the IB identity inspector  Now how am I going to refer to this ViewController programmatically from the AppDelegate  I ve made a variable with the relevant class and turned it into an IBOutlet property  but I don t see any way of being able to refer to the new ViewController in code - any attempt to ctrl-drag a connection doesn t work   i e  within the AppDelegate I can get to the base ViewController like this   MyViewController   self window rootViewController   but how about any other ViewController contained within the storyboard

User · Accepted Answer

Have a look at the documentation for - UIStoryboard instantiateViewControllerWithIdentifier    This allows you to instantiate a view controller from your storyboard using the identifier that you set in the IB Attributes Inspector     EDITED to add example code   UIStoryboard  mainStoryboard    UIStoryboard storyboardWithName   MainStoryboard                                                           bundle  nil    MyViewController  controller    MyViewController   mainStoryboard                      instantiateViewControllerWithIdentifier     lt Controller ID gt

User · Answer

Generally  the system should be handling view controller instantiation with a storyboard  What you want is to traverse the viewController hierarchy by grabbing a reference to the self window rootViewController as opposed to initializing view controllers  which should already be initialized correctly if you ve setup your storyboard properly    So  let s say your rootViewController is a UINavigationController and then you want to send something to its top view controller  you would do it like this in your AppDelegate s didFinishLaunchingWithOptions   UINavigationController  nav    UINavigationController    self window rootViewController  MyViewController  myVC    MyViewController   nav topViewController  myVC data   self data    In Swift if would be very similar   let nav   self window rootViewController as  UINavigationController  let myVC   nav topViewController as  MyViewController myVc data   self data   You really shouldn t be initializing view controllers using storyboard id s from the app delegate unless you want to bypass the normal way storyboard is loaded and load the whole storyboard yourself  If you re having to initialize scenes from the AppDelegate you re most likely doing something wrong  I mean imagine you  for some reason  want to send data to a view controller way down the stack  the AppDelegate shouldn t be reaching way into the view controller stack to set data  That s not its business  It s business is the rootViewController  Let the rootViewController handle its own children  So  if I were bypassing the normal storyboard loading process by the system by removing references to it in the info plist file  I would at most instantiate the rootViewController using instantiateViewControllerWithIdentifier   and possibly its root if it is a container  like a UINavigationController  What you want to avoid is instantiating view controllers that have already been instantiated by the storyboard  This is a problem I see a lot  In short  I disagree with the accepted answer  It is incorrect unless the posters means to remove loading of the storyboard from the info plist since you will have loaded 2 storyboards otherwise  which makes no sense  It s probably not a memory leak because the system initialized the root scene and assigned it to the window  but then you came along and instantiated it again and assigned it again  Your app is off to a pretty bad start

User · Answer

For iOS 13  in SceneDelegate  var window  UIWindow   func scene   scene  UIScene  willConnectTo session  UISceneSession  options  connectionOptions  UIScene ConnectionOptions        guard let windowScene    scene as  UIWindowScene  else   return       window   UIWindow windowScene  windowScene      let storyboard   UIStoryboard name   quot Main quot   bundle  nil     Where  quot Main quot  is the storyboard file name     let vc   storyboard instantiateViewController withIdentifier   quot ViewController quot      Where  quot ViewController quot  is the ID of your viewController     window  rootViewController   vc     window  makeKeyAndVisible

User · Answer

If you use XCode 5 you should do it in a different way    Select your UIViewController in UIStoryboard Go to the Identity Inspector on the right top pane Check the Use Storyboard ID checkbox Write a unique id to the Storyboard ID field   Then write your code      Override point for customization after application launch   if   lt your implementation gt         UIStoryboard  mainStoryboard    UIStoryboard storyboardWithName   Main                                                                bundle  nil       YourViewController  yourController    YourViewController    mainStoryboard        instantiateViewControllerWithIdentifier   YourViewControllerID        self window rootViewController   yourController     return YES

User · Answer

UIStoryboard   storyboard    UIStoryboard storyboardWithName   Tutorial  bundle nil       self window rootViewController    storyboard instantiateInitialViewController

[iphone] Storyboard - refer to ViewController in AppDelegate

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