Sending data through Unwind Segues - ios

Question

I have a custom unwind segue issue. Let me explain my controller setup:
I have a main screen which is a navigation controller with a cell view inside. Within this view, there is a button to add data, and in that view is 4 buttons for additional "types" of data to add. Once a user selects one of those four options, they are presented with a view controller specific to their choice that lets them enter data with a done button. The three screens respectively I will from now on refer to them as Main View, Options View, then Data View(all 4 options follow this convention).
After some tutorials I made a custom unwind segue in Main View's controller class, as follows:
#IBAction func unwindToTables(segue: UIStoryboardSegue) {
//function proto for adding data here
//populateTableWithData(data :ItemData)
}
In the storyboard editor, anytime I control + click from any View Controller to it's exit, it lists my unwind segue properly and this works fine.
I would now like to send data through the unwind. In Data View, I have a Done button that constructs and initializes a class of data, called ItemData to which I would like to pass through the segue.
Most of the questions I found on SO or other sites with this deals with normal segues, and when I try to implement them anyways the application causes a runtime error / does not compile.
Has anyone come into the issue before, and have a solution for said issue? Any help or points in the right direction would be much appreciated!
Edit:
I edited my unwind function as follows:
#IBAction func unwindToTables(segue: UIStoryboardSegue) {
let dataC = segue.sourceViewController as? DataVC
let data : ItemData = dataC!.SubmittedData! //unwrapping error
print(data.Name)
//save data
}
and on top of every New{1-4}ViewController I have the following:
import UIKit
class New1ViewController: DataVC,
and I made a new superclass DataVC:
import Foundation
class DataVC: UITableViewController {
var SubmittedData: ItemData?
}
but now I am getting an unwrapping issue... must I initialize SubmittedData prior?
Edit 2:
Thought I might add the Done button press I am doing...
#IBAction func DonePressed(sender: AnyObject) {
let n = ...
...
let d = ...
super.SubmittedData = ItemData(FieldType: "1", CName: n!, CPhone: p!, CAddress: a!, ShouldBe: s!, Repeats: r!, Starts: b, RemindMe: m!, AdditionalNotes: d!)
}

Answer 1

The UIStoryboardSegue that is passed to your unwindToTables: function has a property sourceViewControllee this will be the instance of your Data view controller.
You need all of your view controllers to inherit from a common superclass, so that you can add the property you need:
class DataVC: UITableViewController {
var submittedData: ItemData?
}
Then you would have something like:
class New1ViewController: DataVC,... {
...
}
Then in your unwind method you can retrieve the submittedData property
#IBAction func unwindToTables(segue: UIStoryboardSegue) {
if let dataVC = segue.sourceViewController as? DataVC {
if let info = dataVC.submittedData {
...
}
}
}