How to perform a transition animation to a new ViewController when a cell is tapped

Question

I'm trying to create a UIViewController transition when a tableView cell is tapped. I'm using a modal segue to go to another Viewcontroller and i use the viewcontroller's transitioningDelegate i'm going to but it still won't perform the animation. I'm not sure if i'm supposed to do it this way in prepareForSegue or didSelectRow . I'm new to ViewController transitions. How can i correct this.

Pop Animator class

class PopAnimator: NSObject, UIViewControllerAnimatedTransitioning {

    func transitionDuration(using pTransitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 1.0
    }

    func animateTransition(using pTransitionContext: UIViewControllerContextTransitioning) {
        let containerView = pTransitionContext.containerView
        guard let toView = pTransitionContext.view(forKey: .to) else { return }
        containerView.addSubview(toView)
        toView.alpha = 1.0
        UIView.animate(withDuration: 1.0, animations: {
            toView.alpha = 1.0
        }) { _ in
            pTransitionContext.completeTransition(true)
        }
    }
}

Destination ViewController

class ThingsTransitionVC: UIViewController {

    @IBOutlet weak var nameLabel: UILabel!
    @IBOutlet weak var detailsLabel: UILabel!
    @IBOutlet weak var titleLabel: UILabel!

    var transitionThing: Thing?

    override func viewDidLoad() {
        super.viewDidLoad()
        if let thing = self.transitionThing {
            self.nameLabel.text = thing.name
            self.detailsLabel.text = thing.details
            self.titleLabel.text = thing.title
        }
    }

    @IBAction func cancelButton(_ sender: UIBarButtonItem) {
        self.presentingViewController?.dismiss(animated: true)
    }
}

Lists ViewController that contains the tableview

class ThingsListVC: UIViewController {
       override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if segue.identifier == "ThingSegue" {
            let navVC = segue.destination as! UINavigationController
            let thingTransitionVC = navVC.topViewController as! ThingsTransitionVC
            let theThing = sender as? Thing
            thingTransitionVC.transitionThing = theThing
            thingTransitionVC.transitioningDelegate = self
        }
    }

     func tableView(_ pTableView: UITableView, didSelectRowAt pIndexPath: IndexPath) {
    let thingSelected = self.objectForIndexPath(pIndexPath)
    self.performSegue(withIdentifier: "ThingSegue", sender: thingSelected)
    pTableView.deselectRow(at: pIndexPath , animated: true)
}

}

extension ThingsListVC: UIViewControllerTransitioningDelegate {
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        let popAnimator = PopAnimator()
        return popAnimator
    }

    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return nil
    }
}

Answer 1

Use UIViewControllerTransitioningDelegate in your source ViewController

  public override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "segueIdentifier1st"
        {

            let controller = segue.destination as! firstVC
            controller.transitioningDelegate = self
            controller.modalPresentationStyle = .custom

        }
        else if segue.identifier == "segueIdentifier2nd"
        {
            let controller = segue.destination as! secondVC

            controller.transitioningDelegate = self

            controller.modalPresentationStyle = .custom
        }
        //interactiveTransition.attach(to: controller)
    }
    override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {

        return true
    }
    // MARK: UIViewControllerTransitioningDelegate

    public func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?
    {
        transition.transitionMode = .present
        if presented.restorationIdentifier!  == "segueIdentifier1st"
        {
            transition.startingPoint = CGPoint(x: btnAddWidget.center.x , y: btnAddWidget.frame.origin.y+50)
        }
        else if presented.restorationIdentifier! == "segueIdentifier2nd"
        {
            //transition.startingPoint = CGPoint(x: self.view.frame.size.width-45, y:45)
            transition.startingPoint = getTransitionOrigin()
        }
        transition.bubbleColor = backgroundThemeColor
        return transition
    }
    public func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        transition.transitionMode = .dismiss
        if dismissed.restorationIdentifier!  == "segueIdentifier1st"
        {
            transition.startingPoint = CGPoint(x: btnAddWidget.center.x , y: btnAddWidget.frame.origin.y+50)
        }
        else if dismissed.restorationIdentifier! == "segueIdentifier2nd"
        {
            //transition.startingPoint = CGPoint(x: self.view.frame.size.width-45, y:45)
            transition.startingPoint = getTransitionOrigin()
        }
        transition.bubbleColor = backgroundThemeColor

        return transition
    }