Use Popover style to dislay new screen

We want new screen appear as a Alert, choos style Popover for new ViewController.

let vc = second()

       

        vc.modalPresentationStyle = .Popover

        var popover = vc.popoverPresentationController   

        if let popover = vc.popoverPresentationController {       

            popover.sourceView = self.view           

            popover.sourceRect = CGRectMake(self.view.center.x,self.view.center.y+180,0,0)           

            vc.preferredContentSize = CGSizeMake(300,360)           

            popover.delegate = self

        }

       

        self.presentViewController(vc, animated: true, completion: nil)

New screen will float on current screen, width 300, height 360.

Need ajust views for new width.