How to change the size of a popover

Set the preferred content size on the view controller being presented not the popoverPresentationController

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) // func for popover
    {
        if segue.identifier == "popoverView"
        {
            let vc = segue.destinationViewController

            vc.preferredContentSize = CGSize(width: 200, height: 300)

            let controller = vc.popoverPresentationController

            controller?.delegate = self
            //you could set the following in your storyboard
            controller?.sourceView = self.view
            controller?.sourceRect = CGRect(x:CGRectGetMidX(self.view.bounds), y: CGRectGetMidY(self.view.bounds),width: 315,height: 230)
            controller?.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)

        }
    }

I fixed it via storyboard : Click on your controller Click on Attribute inspector ViewController> Check Use Preferred Explicit size and input values.