passing instance of different sub classes onto another ViewController in Swift 3 - swift3

Question

I am trying to pass the instance of a created user onto to another view controller. The problem is the user that is passed over depends on type of user is selected. What I mean is I have created many sub-class of the main class User. So for example: Guest, VIP, Child etc and so when an instance is created on first page it is the sub class for that user that is created. I cannot get my head around how I pass the user to the second view controller without the second view controller user property being set to Type User. The problem is type User does not have all properties that sub classes have so in second page I am unable to access all properties that a sub class might have. This is example how I currently have it set:
First screen / view controller
var entrantData: People?
var entrantSelected: EntrantType = .none
#IBAction func generatePass(_ sender: UIButton) {
do{
switch entrantSelected {
case .freechildguest: entrantData = try Child(dateOfBirth: "\(dobTextField.text!)")
case .classicguest: entrantData = ClassicGuest()
case .maintenance: entrantData = try Maintenance(NameAddress(firstName: firstNameTextField.text, lastName: lastNameTextField.text, streetAddress: streetAddressTextField.text, city: cityTextField.text, state: stateTextField.text, zipCode: zipCodeTextField.text, entrantType: .maintenance))
default: break
}
} catch let error {
showAlert(title: "Error", message: "\(error)")
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destViewController = segue.destination as? TicketViewController {
destViewController.dataFromForm = entrantData
}
}
Second screen / view controller
class TicketViewController: UIViewController {
var dataFromForm: People?
So in second View controller I now have the user data in dataFromForm but I want it to be in its sub class so I can get its properties that are only divided in its sub class. E.g. maintenance user has firstname property that child and classicGuest do not.
I suppose I could create all properties that sub class use in the User super class but I feel that defeats the point creating sub classes that have their own unique properties.

Answer 1

One way to solve this issue is to keep the property of type People on the TicketViewController and when trying to access a property that only a certain subclass has, try conditional down casting the People instance to the appropriate subclasses.
Here's a basic example of how you can achieve this:
if let vip = dataFromForm as? VIP {
//access VIP properties
} else if let guest = dataFromForm as? Guest {
//access guest properties
}

Answer 2

Another thing you can do is down cast to the protocol itself. This may make it easier in certain situations when there are multiple subclasses conforming to the same protocol.
if let entrant = entrantData as? Nameable {
fullNameLabel.text = entrant.fullName
}
So the above code would not be executed on child or classicGuest since they do not conform to the Nameable protocol.