App crash when successfully passing data - swift

Question

I have a simple app. A table view passing user information from 1 view controller to another. It successfully prints out my user object and I can see the data in the console, however when I go to extract the data from the object into my view it does not display
#IBOutlet weak var chatPartnerLabel: UILabel!
var user: User? {
didSet {
print(user) //This prints out all information fine
chatPartnerLabel.text = user?.firstName //This crashes the app because chatPartnerLabel.text is nil
}
}
override func viewDidLoad() {
super.viewDidLoad()
chatPartnerLabel.text = user?.firstName //This comes up as nil
}
I have also tried hardcoding the label to see if it works properly
chatPartnerLabel.text = "My text" //Changes the label to My Text
I have also tried putting user?.firstName in viewDidAppear and viewWillAppear both display an empty label.
As you can see in the console my user is there with data. The crash I get when attempting to set is coming up as nil
What am I doing wrong to successfully change my chatPartnerLabel to either the name or firstname?

Answer 1

class User {
var firstName = "fn"
}
///uiviewcontroller:
#IBOutlet weak var chatPartnerLabel: UILabel!
var user: User? {
didSet {
print(user) //This prints out all information fine
chatPartnerLabel.text = user?.firstName //This crashes the app
}
}
both:
override func viewDidLoad() {
super.viewDidLoad()
user = User()
and:
override func viewDidLoad() {
super.viewDidLoad()
chatPartnerLabel.text = user?.firstName
work! I've tested!
We need more information and correct callstack. May be chatPartnerLabelis nil while unwrapping.

Answer 2

if you are setting user in segue or before pushing/presenting controller, it will crash, because label is not instantiated yet. That's why you have to rewrite your code to:
#IBOutlet weak var chatPartnerLabel: UILabel! {
didSet {
print(user?.firstName) // just for check
chatPartnerLabel.text = user?.firstName
}
}
var user: User? {
didSet {
print(user) //This prints out all information fine
}
}

Answer 3

This works Swift 3. I added a Boolean control to know when viewDidLoad is called.
var user: (firstName : String, lastName : String, controlView : Bool)? {
didSet {
if (self.user?.controlView)! {
print(user!)
chatPartnerLabel.text = user?.firstName
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
user?.controlView = true
}