iOS13：PopoverPresentationController-缺少箭头的边框

Question

与本帖子的主题相同：ios13 UIPopoverViewController showing UITableViewController - Safe Area problems / Missing parts of table

但是就我而言，它不是一个UITableViewController，iPad上的一个弹出窗口中的任何View Controller自iOS13起都存在相同的问题。

我对重叠的内容没有问题，只是边框。

App screenshot

let popoverContent = self.storyboard!.instantiateViewController(withIdentifier: controllerName) as! SelectSceneViewController
popoverContent.preferredContentSize = CGSize(width: 700,height: 500)

let nav = UINavigationController(rootViewController: popoverContent)
nav.modalPresentationStyle = UIModalPresentationStyle.popover
nav.navigationBar.barStyle = navbarStyle
nav.view.layer.cornerRadius = 10
nav.view.layer.borderColor = UIColor.white.cgColor
nav.view.layer.borderWidth = 2

let popover = nav.popoverPresentationController
popover?.sourceView = button
popover?.sourceRect = button.bounds

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

Answer 1

我找到了答案。我必须实现自己的UIPopoverBackgroundView。例如：https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/bk2ch09p476popovers/ch22p751popovers/MyPopoverBackgroundView.swift