Swift - Set a UI element from outside - ios

Question

I have this UIViewController
import UIKit
class UIViewController1: UIViewController {
#IBOutlet weak var someTitle: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
And I am trying to set someTitle when I instantiate it from another view controller:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func viewDidAppear(animated: Bool) {
let stb = UIStoryboard(name: "Main", bundle: nil)
let vc1 = stb.instantiateViewControllerWithIdentifier("someSTBID") as! UIViewController1
vc1.someTitle.text = "My Title" // it fails here!!!!!
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
The reason it fails at the line above is that I was trying to force unwrapping a nil optional, which is someTitle.
Please show me a way to set someTitle in this situation.

Answer 1

Your second UIViewController hasn't been loaded yet, so the someTitle IBOutlet will be nil. You got two options:
The easy one: you force the load of the second UIViewController, for example: vc1.view is enough and then you set it (I don't recommend this)
The proper one: you let the second UIViewController be responsible for setting its own title at the right time. If you need to pass the "My title", you can simply pass it via a function like configureVc(title: String), or by exposing a variable like var title: String, so on viewDidLoad of the second UIViewController you would someTitle.text = title.

Answer 2

Do you need it to go into the superclass viewDidAppear, because it should work if you put it into the superclass viewDidLoad(). I hope that helps you and future viewers.