所以我想出了如何在iOS8中显示popover：

So I figured out how to show the popover in iOS8:

在iOS7.1中，我使用

In iOS7.1, I was controlling the size of the popover content using

// set content size
[popOverController setPopoverContentSize:CGSizeMake(SIZE_POPOVER_WIDTH, SIZE_POPOVER_HEIGHT)];

在iOS8中，我将此更改为设置弹出视图中嵌入的视图的内容大小setPreferredContentSize属性如下：

In iOS8, I changed this to setting the content size of the view embedded in the popover view using the setPreferredContentSize property as follows:

dropdownVC.preferredContentSize = CGSizeMake(SIZE_POPOVER_WIDTH, SIZE_POPOVER_HEIGHT);

进行此更改后，将显示具有正确计算高度的弹出窗口。

After making this change, the popover with the correct calculated height is being displayed.