如何从自定义导航栏的右按钮显示PopoverViewController？

// 创建自定义导航栏按钮
let customButton = UIBarButtonItem(title: "显示", style: .plain, target: self, action: #selector(showPopover))

// 设置为导航栏的右按钮
navigationItem.rightBarButtonItem = customButton

// 点击按钮时的事件处理
@objc func showPopover() {
    // 创建PopoverViewController实例
    let popoverVC = PopoverViewController()
    
    // 设置PopoverViewController的内容和样式
    
    // 设置PopoverViewController的弹出位置和大小
    popoverVC.preferredContentSize = CGSize(width: 200, height: 200)
    popoverVC.modalPresentationStyle = .popover
    
    // 将PopoverViewController添加到当前视图控制器中并显示
    if let popover = popoverVC.popoverPresentationController {
        popover.sourceView = customButton
        popover.sourceRect = customButton.bounds
        popover.permittedArrowDirections = .up
        present(popoverVC, animated: true, completion: nil)
    }
}