ios - UIAlertController 和 displayShareSheet 在 iPad 上崩溃

Question

我在 View 中有一个 UIButton。 UIButton 的位置类似于

我有一个 @IBAction，它在单击 UIButton 时触发

@IBAction func shareButtonClicked(_ sender: AnyObject) {
    Flurry.logEvent("Share button tapped");


    let textToShare = quotetext.text 

    // 1.
    // Create and initialize a UIAlertController instance.
    //
    let alertController = UIAlertController(title: nil,
                                            message: nil,
                                            preferredStyle: .actionSheet)

    // 2.
    // Initialize the actions to show along with the alert.
    //
    let copyAction = UIAlertAction(title:"Copy Quote to clipboard",
                                   style: .default) { (action) -> Void in
                                    let pasteboard: UIPasteboard = UIPasteboard.general
                                    pasteboard.string = self.quotetext.text;
    }

    let defaultAction = UIAlertAction(title:"Share Quote",
                                      style: .default) { (action) -> Void in
                                        // We have contents so display the share sheet
                                        self.displayShareSheet(shareContent: textToShare)

    }

    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) { (action) in
        // ...
    }

    // 3.
    // Tell the alertController about the actions we want it
    // to present.
    //
    alertController.addAction(copyAction)
    alertController.addAction(defaultAction)
    alertController.addAction(cancelAction)


    // 4.
    // Present the alert controller and associated actions.
    //
    self.present(alertController, animated: true, completion: nil)

}

这会产生如下所示的警报

选择“共享报价”时，警报会提出一个sharesheet。

这个@IBAction 在 iPhone 上工作，但在 iPad 上崩溃。错误信息是

'NSGenericException', reason: 'Your application has presented a UIAlertController () of style UIAlertControllerStyleActionSheet. The modalPresentationStyle of a UIAlertController with this style is UIModalPresentationPopover. You must provide location information for this popover through the alert controller's popoverPresentationController. You must provide either a sourceView and sourceRect or a barButtonItem. If this information is not known when you present the alert controller, you may provide it in the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.'

我试图通过尝试类似的方法来解决这个问题

    //iPad

    alertController.popoverPresentationController?.sourceView = viewBottom
    alertController.popoverPresentationController?.sourceRect = viewBottom.bounds
    alertController.popoverPresentationController?.permittedArrowDirections = UIPopoverArrowDirection.down;

此修复程序不起作用。警报错误地定位在“viewBottom”上方，当我单击“defaultAction”按钮时 - 它再次崩溃并显示上述错误消息。

我有点不知如何解决这个问题。任何人都可以对此提出一些建议吗？我尝试过各种使用方式

the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.'

在我的代码中，但没有成功。任何建议对此表示赞赏。谢谢。

Answer 1

替换这些行:

alertController.popoverPresentationController?.sourceView = viewBottom
alertController.popoverPresentationController?.sourceRect = viewBottom.bounds
alertController.popoverPresentationController?.permittedArrowDirections = UIPopoverArrowDirection.down;

与:

if let button = sender as? UIButton {
    alertController.popoverPresentationController?.sourceView = button
    alertController.popoverPresentationController?.sourceRect = button.bounds
}

您还必须在 displayShareSheet 方法中设置共享表的 popoverPresentationController。您可能应该将 UIButton 作为参数传递给该方法，以便您可以在那里使用它。