Swift: Cannot modify images in popup - ios

Question

Beginner swift-user here. I want to open a pop up connected to a seperate view controller (P2_Gift_Pop_Up) from the main view controller. To this end I include the following in a code snippet in my main view controller
let vc = P2_Gift_Pop_Up()
vc.modalPresentationStyle = .overCurrentContext
present(vc, animated: true, completion: nil)
This starts running code in the popup window (a print statement works anyway), so so far, so good.
However, when I try to modify some elements in the view connected to the view controller I get a
Thread 1: Fatal error: Unexpectedly found nil while unwrapping an
Optional value. Here is the code in its entirety.
import UIKit
class P2_Gift_Pop_Up: UIViewController {
#IBOutlet weak var Slot1: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
Slot1.setImage(UIImage(named: "Card 2 Red"), for: .normal)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
Although I have (via another answer on this site) an understanding of what the msg means, I don't understand why I get it in this context, and how to fix it. It might also bear emphasis that although code starts running after the P2_Gift_Pop_Up call, the corresponding view is not shown.

Answer 1

You need to present your controller like this(you need to set your storyboard ID and then add this in identifier):
let storyBoard = UIStoryboard(name: "main", bundle: Bundle.main)
let vc = storyBoard.instantiateViewController(withIdentifier: "your storyboard id") as! P2_Gift_Pop_Up
vc.modalPresentationStyle = .overCurrentContext
present(vc, animated: true, completion: nil)
Your app is crashing because of your button(Slot1) not have a memory so you need to present like above.

Answer 2

#JogendarChoudhary told you what to do, but didn't really explain why.
When you create your P2_Gift_Pop_Up with
let vc = P2_Gift_Pop_Up()
You aren't initializing it properly. It doesn't get a chance to load it's views from it's XIB file/storyboard.
Assuming you have your view controller defined in your main app storyboard, you need to load the view controller from the storyboard.
You should add a unique identifier to your view controller in your storyboard, and then load it using that identifier. (Using the name of the class as the identifier is as good a choice as any.)
The UIViewController class has a property storyboard which will contain the storyboard from which it's loaded. Usually that's your app's main storyboard, and what you want. Thus:
if let vc = storyboard?.instantiateViewController(withIdentifier: "P2_Gift_Pop_Up id")
as? P2_Gift_Pop_Up {
vc.modalPresentationStyle = .overCurrentContext
present(vc, animated: true, completion: nil)
} else {
print("error creating P2_Gift_Pop_Up")
}