Segue transitions to the wrong page Swift Xcode

Question

I am trying to create a series of pages that work in tandem using custom segues. These segues work fine until I have them execute in a certain series. From VC1 I go to VC2 via the default modal segue (it pops up over the original segue). Then, from VC2 I go to VC3 using a custom horizontal segue (code below). Finally, I go back from VC3 to VC1 using a custom unwind horizontal segue. The problem is that when I go back to VC1, VC2 appears instead. I checked and ViewDidLoad does not execute in VC2 when it appears, but I can still interact with it when triggered. My best guess as to what is happening is that VC2 covers VC1 so when I go back to VC1, VC2 is displayed on top of it. Even if this is the problem, I don't know how to fix it. Code below:

Horizontal Segue:

class HorizontalSegue: UIStoryboardSegue {

    override func perform() {
        let src = self.source as UIViewController
        let dst = self.destination as UIViewController

        src.view.superview?.insertSubview(dst.view, aboveSubview: src.view)
        dst.view.transform = CGAffineTransform(translationX: src.view.frame.size.width, y: 0)

        UIView.animate(withDuration: 0.2, delay: 0.0, options: [.curveEaseOut], animations: {
            dst.view.transform = CGAffineTransform(translationX: 0, y: 0)
        },
            completion: { finished in
                src.present(dst, animated: false, completion: nil)
        })
    }
}

Unwind Horizontal Segue:

class UnwindHorizontalSegue: UIStoryboardSegue {

    override func perform() {
        let src = self.source as UIViewController
        let dst = self.destination as UIViewController

        src.view.superview?.insertSubview(dst.view, belowSubview: src.view)
        src.view.transform = CGAffineTransform(translationX: 0, y: 0)

        UIView.animate(withDuration: 0.2, delay: 0.0, options: [.curveEaseIn], animations: {
            src.view.transform = CGAffineTransform(translationX: src.view.frame.size.width, y: 0)
        },
            completion: { finished in
                src.dismiss(animated: false, completion: nil)
        })
    }
}

Answer 1

The first thing I noticed is that you said ViewDidLoad is not called for VC2. Please see if ViewDidAppear (or will appear) is being called instead.

ViewDidLoad is only called when the view loads (initially, when it wasn't there before). ViewDidAppear should fire always, when the view is brought into the user's screen.

After that, log dst in your custom UIStoryBoardSegue. If that's an instance of VC2, you are simply pushing the wrong view controller.

I also see you're using src.present and src.dismiss in your UIStoryboardSegue. This means you're not actually pushing views, but presenting them "on top" of an active view controller. Try to rethink that logic, since this is very much likely where the problem lies.

I would rather try and push the view controllers (normally, instead of 'presenting' them) and change the UIStoryboardSegue appearance to fake the animation if that's what you're after.