Popoverの2つの実装方法を比較する ref: http://qiita.com/hsylife/items/9df3dee1fc70b244da8c

ViewController.swift

class ViewController: UIViewController, UIPopoverPresentationControllerDelegate {

    @IBAction func tapModalPresentationStyle(_ sender: UIButton) {
        //Prepare the instance of ContentViewController which is the content of popover.
        let contentVC = ContentViewController()
        //define use of popover
        contentVC.modalPresentationStyle = .popover
        //set size
        contentVC.preferredContentSize = CGSize(width: 300, height: 300)
        //set origin
        contentVC.popoverPresentationController?.sourceView = view
        contentVC.popoverPresentationController?.sourceRect = sender.frame
        //set arrow direction
        contentVC.popoverPresentationController?.permittedArrowDirections = .any
        //set delegate
        contentVC.popoverPresentationController?.delegate = self
        //present
        present(contentVC, animated: true, completion: nil)
    }

    /// Popover appears on iPhone
    func adaptivePresentationStyle(for controller: UIPresentationController, traitCollection: UITraitCollection) -> UIModalPresentationStyle {
        return .none
    }

}