PopOver Controller

    // present popover EditingPopoverController to change collage corners
    @objc func changeCollageCorners() {

        let popOverView = self.storyboard?.instantiateViewController(withIdentifier: "EditingPopoverController") as! EditingPopoverController

        let nav = UINavigationController(rootViewController: popOverView)
        nav.modalPresentationStyle = UIModalPresentationStyle.popover
        let popover = nav.popoverPresentationController
        popOverView.preferredContentSize = CGSize(width: 200,height: 80)
        popover!.delegate = self
        popover!.sourceView = navigationBaar.leftBarBut.imageView
        popover!.sourceRect = navigationBaar.leftBarBut.bounds

        popOverView.slideProtocol = self

        self.present(nav, animated: true, completion: nil)
    }