iOS swift 5: 關於 "UIAlertController actionSheet Exception"

解決方案來源:
1: 顯示警告訊息和選單的 UIAlertControlle
2: Swift 4 Tutorial : Show PopOver with TableView from Scratch (Source file link in 
description)
3: ActionSheet Popover on iPad in Swift

 *** Terminating app due to uncaught exception

 'NSGenericException', reason: 'Your application has presented a

  UIAlertController (<UIAlertController: 0x1160ef600>) of

   style UIAlertControllerStyleActionSheet from XXX.MainViewController (<XXX.MainViewController: 0x116036600>).

   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.'

意思就是沒有設置UIAlertController這個彈出窗口的位置信息

 @IBAction func BtnTestOnClick(_ sender: Any)

 {

    

  let alertController = UIAlertController(title: nil, message: "Alert message.", preferredStyle: .actionSheet)

  let defaultAction = UIAlertAction(title: "Default", style: .default, handler: { (alert: UIAlertAction!) -> Void in

    //  Do some action here.

  })

  let deleteAction = UIAlertAction(title: "Delete", style: .destructive, handler: { (alert: UIAlertAction!) -> Void in

    //  Do some destructive action here.

  })

  let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: { (alert: UIAlertAction!) -> Void in

    //  Do something here upon cancellation.

  })

  alertController.addAction(defaultAction)

  alertController.addAction(deleteAction)

  alertController.addAction(cancelAction)

  

  if let popoverController = alertController.popoverPresentationController {

   popoverController.sourceView = self.view

   popoverController.sourceRect = CGRect(x: self.view.bounds.midX, y: self.view.bounds.midY, width: 0, height: 0)

   popoverController.permittedArrowDirections = []

  }

  self.present(alertController, animated: true, completion: nil)

 }