In Xcode, I want to make a screen transition, but it says Could not cast value of type 'UIViewController'

The transition destination ViewController is instantiated incorrectly.

The storyboard.instantiateInitialViewController() instantiates with the IsInitialViewController designated in the target Storyboard and indicated by a non-left arrow on the Interface Builder as follows:(Only one can exist on one storyboard.)

Your linked article uses a method called instantiateViewControllerWithIdentifier(_:) instead of instantiateInitialViewController().In other words, each View Controller must be named (Storyboard ID) on the Storyboard and instantiated with that name.(Otherwise, iOS won't know which View Controller it wants to instantiate.?)

(Storyboard ID can be anything as long as it is consistent with the program code side.I often use the class name as it is.)

After setting the Storyboard ID correctly as shown above, try rewriting the previous line as follows:

let vc=storyboard.instantiateViewController(withIdentifier: "Session") as!SessionViewController

(The Swift version has been upgraded since the beginning of the article, so the method name looks different.)

However,

I was going to use Segue, but it crashed and I didn't see any error statements, so I'm using a method that doesn't use Segue

Based on the description, it seems that the workaround is not working well because they don't understand how Storyboard and Segue work well and run away as if they don't get any immediate crashes or error messages.

If the above correction successfully solves the problem of your question, please try to create an app that does not crash using Segue.Of course, the stack overflow here should be of some help.