纯代码实现 presentAsPopView

在iOS中，segue的class为UIStoryboardSegue，用于storyboard中不同视图控制器间转场，即从一个视图控制器转场到另一个视图控制器。Segue的起点必须是一个view或者定义某些操作的对象，如：UIBarButtonItem、UIControl和UIGestureRecognizer。

Segue分为以下几种类型，其中Push、Modal、Popover和Replace已弃用。

• Show

• Show Detail

• Present Modally

• Present as Popover

• Custom

• Push

• Modal

• Popover

• Replace

在iPhone中有Show、Show Detail、Present Modally、Custom四种不同类型，iPad中有Show、Show Detail、Present Modally、Present as Popover、Custom五种不同类型。

我想要阐释的是Present as Popover，在iPhone和iPad上为两种展开模式，swift代码实现如下：

        let navigationFilterVc = UIStoryboard(name: "Search", bundle: currentBundle).instantiateViewController(withIdentifier: "SearchViewController") as? UINavigationController
        if let navVc = navigationFilterVc,let filterVc = navVc.children.first as? TeacherFilterContainerViewController  {
           //这个模式只在iPad上生效
            navVc.modalPresentationStyle = .popover
            let popoverPresentationController = navVc.popoverPresentationController
            if let _popoverPresentationController = popoverPresentationController{
                _popoverPresentationController.barButtonItem = barButton
                _popoverPresentationController.sourceView = self.view
               //修改弹出来的popView的大小
                let size = _popoverPresentationController.sourceRect.size
                navVc.preferredContentSize = CGSize(width: size.width, height: size.height + 800)
            }
            self.present(navVc, animated: true, completion: nil)
        }

效果如下图所示