Swift - Access different View Controllers in App Delegate - swift

Question

In app delegate, with a simple app having only 2 screens:
first screen is a Table View Controller embedded in Navigation Controller
second screen is a View Controller which is used to add items to the first screen table via protocol/delegate/segue
And this is the code for didFinishLaunchingWithOptions in app delegate that I can reference the first screen as viewController[0]:
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
let navController = self.window?.rootViewController as! UINavigationController
let courseListController = navController.viewControllers[0] as! CourseListController
courseListController.managedObjectContext = self.managedObjectContext
return true
}
How can I reference the screens at above, below and next to the center sreen? Please suggest me a solution. Thank you!

Answer 1

It's important to keep in mind that the view controller objects for all of the "peripheral" view controllers in your story board won't actually exist until the segue to get to them is executed, so there's no way to get access to them directly from the app delegate. Instead, you need to push state to each child view controller as it's created, from whatever the source view controller is. Segues are the appropriate way to do this.
You will probably want to assign each of the segues from the central view controller a unique segue identifier in Interface Builder. Click on the segue, then enter it here:
In the central view controller, implement prepareForSegue(_:sender:), doing something like the following:
func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject) {
switch segue.identifier {
case "SegueIdentifier1":
guard let destination = segue.destinationViewController as? ViewController1 else {
return
}
// set up your view controller here
case "SegueIdentifier2":
guard let destination = segue.destinationViewController as? ViewController2 else {
return
}
// set up your view controller here
// add additional segues as required
default:
break // unknown segue
}
}

Answer 2

Go to each view Controller you want to reference and in the identity inspector, add some string to its StoryBoard ID.
next to reference it from the new ViewController (say, XViewController) to (say, YViewController)
do this :
var referencedViewController = self?.storyboard.
instantiateViewControllerWithIdentifier("referenceViewID") as! YViewController
self.presentViewController(referencedViewController,
animated: true, completion: nil)