UIView is nil in prepareForSegue method - ios

Question

sorry for confusing title, I didn't know how to make it more meaningfull.
I was implementing information window using this example: github
I have added few labels into popView and linked them to secondaryVieController.
I have amended prepareForSegue method in PrimaryViewController to:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showInfo" {
let info = segue.destinationViewController as! SecondaryViewController
info.adrLabel.text = branch.address
info.nameLabel.text = branch.name
info.telLabel.text = branch.tel
dim(.In, alpha: dimLevel, speed: dimSpeed)
}
}
But when I run it i get error "fatal error: unexpectedly found nil while unwrapping an Optional value"
it is because info.popupView is nil.
But can you explain me how should I set it? And why it is working fine if there are no any additional labels.
Thanks.

Answer 1

The first method where you will be access this
info.adrLabel.text = branch.address
info.nameLabel.text = branch.name
info.telLabel.text = branch.tel
values will be viewDidLoad() of SecondaryViewController.
You need to create variables and assign values in those variables and in the viewDidLoad() you can use those variables to assign the value to your labels.

Answer 2

You are getting nil because you are trying to set values before the view has loaded from your prepareForSegue method. Instead, setup some variables in your SecondaryViewController to hold the values and set up your labels in viewDidLoad:
class SecondaryViewController {
var address: String?
var name: String?
var tel: String?
override func viewDidLoad() {
adrLabel.text = address
nameLabel.text = name
telLabel.text = tel
}
}
Now all you need to do in your prepareForSegue is:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showInfo" {
let info = segue.destinationViewController as! SecondaryViewController
info.address = branch.address
info.name = branch.name
info.tel = branch.tel
dim(.In, alpha: dimLevel, speed: dimSpeed)
}
}

Answer 3

As a general rule you should not try to manipulate another view controller's views directly. That violates the principle of encapsulation. You should consider them private.
Instead, add properties to your destination view controller and set those properties. Then in your destiination view controller's viewWillAppear method install the values from those properties into the appropriate views.
That way if you later change your view controller's views you only have to change the code in one place (the view controller)
(Plus, in situations like your prepareForSegue function, it doesn't work.)