6.swift

class CustomTransition: NSObject, UIViewControllerTransitioningDelegate {
    
    // ...
  
    let interaction = UpToDownIneraction()
    
    func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        return nil
    }
    
    
    func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        print(interation.interacting)
        return interaction.interacting ? interaction : nil
    }
}