How to include an ImageView into a Custom Segue? - ios

Question

I'm attempting to create a custom segue where the order of the animation goes
1st UIViewController -> ImageView -> 2nd UIViewController
The code I have works, but for some reason the ImageView is black. I've tried using various images and literal image sources, but it's still black.
Here's some pictures for a better understanding-
1 (As the first UIViewController is replaced by the ImageView)
2 (As the ImageView is replaced by the second UIViewController)
/**
This segue transitions by dragging the destination UIViewController in from the right and replacing the old UIViewController by pushing it off to the left. This Segue also contains an ImageView that is between the two UIViewControllers.
*/
class CustomSegue2: UIStoryboardSegue {
override func perform() {
// Assign the source and destination views to local variables.
let firstView = self.source.view as UIView!
let secondView = UIImageView()
let thirdView = self.destination.view as UIView!
// Get the screen width and height.
let width = UIScreen.main.bounds.size.width
let height = UIScreen.main.bounds.size.height
// Set properties of secondView
secondView.frame = CGRect(x: width, y: 0, width: width, height: height)
secondView.contentMode = UIViewContentMode.scaleToFill
secondView.image = #imageLiteral(resourceName: "orangeRedGradient_MESH_tealGreenGradient")
// Specify the initial position of the destination view.
let rect = CGRect(x: width + width, y: 0.0, width: width, height: height)
thirdView?.frame = rect
// Access the app's key window and insert the destination view above the current
let window = UIApplication.shared.keyWindow
window?.insertSubview(thirdView!, aboveSubview: firstView!)
// Animation the transition.
UIView.animate(withDuration: 10, animations: { () -> Void in
firstView?.frame = firstView!.frame.offsetBy(dx: -width-width, dy: 0.0)
secondView.frame = secondView.frame.offsetBy(dx: -width-width, dy: 0.0)
thirdView?.frame = thirdView!.frame.offsetBy(dx: -width-width, dy: 0.0)
}) { (Finished) -> Void in
self.source.present(self.destination, animated: false, completion: nil)
}
}
}

Answer 1

secondView never appears because at no time do you insert it into the interface.
(I would describe your code overall as completely wrong-headed — if you want a custom transition, you should be writing proper custom transition animation code. But that answers the question of why the image view is "black" — it isn't black, it is completely absent.)