Segue to UIViewController in different UINavigationController - swift

Question

I have the following setup:
I have a UIViewController embedded in a UINavigationController. I have a second UIViewController embedded in a second UINavigationController. I need to call the second UIViewController in two ways. I have two buttons set up on the first UIViewController. The first button has a segue created by control-click-drag between the button and the second UINavigationController. When I click the button, the second view controller displays. The second button calls the created segue using performSegueWithIdentifier like this:
#IBAction func segueTwoButton(sender: AnyObject) {
performSegueWithIdentifier("ShowSecondView", sender: self)
}
In both cases the second view controller displays correctly.
But, I have some information that I want to pass. So in the prepareForSegue function, I have this:
let vc = segue.destinationViewController as! SecondViewController
This fails, because the segue is going through the second UINavigationController to get to the second UIViewController.
I've come up with two ways of handling this.
I can use the following in the prepareForSegue
let vc = segue.destinationViewController.childViewControllers[0] as! SecondViewController
I can add a UINavigationController class and then pipe it through there, but that seems like a lot of work to do this.
Both of these ways work, but is this the best way, or is there some other way that I should consider handling it?
Second question - Assuming that I do it this way and put a UINavigationController class in so that I can pass the information along, what is the proper way to unwind? I can create an unwind segue that will go straight from the second view controller, back to the first, but is it acceptable to do it this way? Or would I need to unwind to the UINavigationController class and then to the first view controller?

Answer 1

I'm not sure why you decided to embed another navigation controller within another. Generally, if you embed a navigation controller one time that will suffice for the rest after you've set up your other segues. So first thing's first delete that second nav controller.
Secondly, from experience, I would always avoid control dragging from anything other the view controller itself. Otherwise, you get duplicate calls to perform segues. So go ahead and delete all remnants of the prior segues you created with the buttons. Instead, Control drag from the top yellow view controller icon to the next view controller. make sure you name the segue arrow so that you can properly performsegueWithIdentifier
Now you should have First View directly segued to the Second View. This will be easier to pipe or funnel information through the segue function exactly like you had coded above
let vc = segue.destinationViewController as! SecondViewController

Answer 2

Global Variable ( will replace segue funneling information )
Lets take this as an example. Say I wanted to recored the user's name on the first view controller.
// First View Controller
private let userName: String
// After that we can create a new object called NameSingleton
class NameSingleton {
// NameSingleton.swift
var UserName:String = " " // Since its global this value will change
static let sharedinstance = NameSingleton()
}
// Now hop back over to your first ViewController
// before you trigger your segue assign whatever data you need to your
// singleton. In this case, a name.
// First View Controller.swift
#IBAction func segueTwoButton(sender: AnyObject) {
NameSingleton.sharedInstance.UserName = "Hi"
performSegueWithIdentifier("ShowSecondView", sender: self)
}
// Now if you go to the second view controller and access it, the name
// will be stored in the singleton. (Great for moving huge pieces info
// (i.e. structs, objects, lists)