UIAlertController is Crashed (iPad)

Question

To keep it device independent, rather use it as shown in the snippet below. This code will return nil for popoverPresentationController on an iPhone / compact size device, so you can safely use it in universal projects.

if let popoverPresentationController = shareMenu.popoverPresentationController {
    popoverPresentationController.sourceView = self.view
    popoverPresentationController.sourceRect = sender.bounds
}
self.presentViewController(shareMenu, animated: true, completion: nil)

try this code:

shareMenu.popoverPresentationController.sourceView = self.view
shareMenu.popoverPresentationController.sourceRect = CGRectMake(self.view.bounds.size.width / 2.0, self.view.bounds.size.height / 2.0, 1.0, 1.0)

self.presentViewController(shareMenu, animated: true, completion: nil)

Swift 4

popoverPresentationController.permittedArrowDirections = .init(rawValue: 0)
popoverPresentationController.sourceView = self.view
popoverPresentationController.sourceRect = CGRect(x: self.view.bounds.midX, y: self.view.bounds.midY, width: 0, height: 0)

reference: ActionSheet Popover on iPad in Swift

create popoverController :

let alertController = UIAlertController(title: nil, message: "Alert message.", preferredStyle: .actionSheet)
self.present(alertController, animated: true, completion: nil)

if you want show alert with indicator view should:

if let popoverController = alertController.popoverPresentationController {
    popoverController.barButtonItem = sender
}

with indicator

show alert in center:

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) 
}

center with indicator

center no indicator:

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 = []
}

center no indicator