将弹出框锚定到textView iOS中选定textRange的矩形

我试图从

UIMenuItem

呈现一个popover，其中锚点是

textView

中选定文本的矩形。我有以下代码：

func pickColor(sender: UIMenuItem) {
    let range = noteTextView.selectedTextRange
    let beginningOfSelection = noteTextView.caretRect(for: (range?.start)!)
    let endOfSelection = noteTextView.caretRect(for: (range?.end)!)

    let storyboard: UIStoryboard = UIStoryboard(name: "ColorPicker", bundle: nil)
    let colorVC = storyboard.instantiateViewController(withIdentifier: "ColorPickerViewController") as UIViewController
    colorVC.modalPresentationStyle = .popover
    let popover: UIPopoverPresentationController = colorVC.popoverPresentationController!
    popover.sourceView = noteTextView
    popover.sourceRect = CGRect(x: (beginningOfSelection.origin.x + endOfSelection.origin.x)/2, y: (beginningOfSelection.origin.y + beginningOfSelection.size.height)/2, width: 0, height: 0)
    present(colorVC, animated: true, completion: nil)
}

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应用程序在

colorVC.modalPresentationStyle=.popover

行中崩溃。有人能告诉我这是怎么回事吗？谢谢！：）

这个确切的代码对我有用。你确定你的“colorVC”不是零吗？不过，我忘了在界面生成器中指定viewController ID，谢谢！