实现这种效果：

5700B8B6-EFE9-485C-8EAA-F84ED622015A.png

popView是一个VC，里边搞了一个tableView ，主视图是ViewController，在里边对这个popVC进行折腾。在这里这个popView的大小是通过调整UIViewController的这个属性：

//The preferred size for the view controller’s view.
self.preferredContentSize = CGSizeMake(150, 305)

接下来是ViewController.swift

import UIKit

class ViewController: UIViewController,UIPopoverPresentationControllerDelegate {
    // 自定义的popVC
    var itemPopVC:XXPopViewController!

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.whiteColor()
        self.navigationItem.rightBarButtonItem = UIBarButtonItem.init(barButtonSystemItem: UIBarButtonSystemItem.Add, target: self, action: #selector(ViewController.actionPop))
        
    }
    // nav的右边按钮添加的action
    func actionPop() {
        self.itemPopVC = XXPopViewController()
// 设置显示的模态
        self.itemPopVC.modalPresentationStyle = .Popover
// 设置弹出的角放在哪个位置，也可以使用sourceView与sourceRect指定位置
        self.itemPopVC.popoverPresentationController?.barButtonItem = self.navigationItem.rightBarButtonItem
// 设置尖尖角指向        
        self.itemPopVC.popoverPresentationController?.permittedArrowDirections = .Up
// 设置代理
        self.itemPopVC.popoverPresentationController?.delegate = self
        self.presentViewController(itemPopVC, animated: true, completion: nil)
    }
    // UIPopoverPresentationControllerDelegate代理方法
    func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
        print(controller)
        return .None
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}