Presenting custom popup from popup then dismissing first popup causes flicker - ios

Question

Currently I create a custom popup A then when a button in it is pressed dismiss it and in the completion handler create a new popup B.
Both popups are similar in that they use a black view with alpha set to a value to simulate the grayed out screen affect that a standard alert provides.
However dismissing A before creating B causes a flicker. I would like to create B before dismissing A but haven't found a good way to do this.
Ideas on how to do this and avoid the flicker?
I'm thinking of putting the black view with the alpha set in the view controller screen that shows popup A and turning it on when popup A is shown and off when popup B is dismissed. This doesn't seem like the best solution however. Another way would be to have a single popup and show hide controls but this seems not a good solution either because it makes the storyboard VC messy.
Here's how the code looks now:
From a menu the popup A is created:
let storyBoard = UIStoryboard(name: "MenuStoryboard", bundle: nil)
let aPopup = storyBoard.instantiateViewController(withIdentifier: "Popup_A")
present(aPopup, animated: false, completion: nil)
Then from button action of Popup A:
self.dismiss(animated: false) {
let storyBoard = UIStoryboard(name: "MenuStoryboard", bundle: nil)
let bPopup = storyBoard.instantiateViewController(withIdentifier: "PopUp_B")
if let topViewController = UIApplication.shared.topMostViewController {
topViewController.present(bPopup, animated: false, completion: nil)
}
}
And the extensions:
extension UIViewController {
var topMostViewController : UIViewController {
if let presented = self.presentedViewController {
return presented.topMostViewController
}
if let navigation = self as? UINavigationController {
return navigation.visibleViewController?.topMostViewController ?? navigation
}
if let tab = self as? UITabBarController {
return tab.selectedViewController?.topMostViewController ?? tab
}
return self
}
}
extension UIApplication {
var topMostViewController : UIViewController? {
return self.keyWindow?.rootViewController?.topMostViewController
}
}

Answer 1

The way you do is not recommended, a View Controller should not be concerned of "dismissing itself" and then "asking" another view controller to present a new view controller.
I'd use delegation from PopupA to communicate back to whatever object presented it. That object SHOULD dismiss the PopupA view controller.
Once completed, you could try to display PopupB.