How to present UIActivityViewController on iPhone and iPad

Presenting UIActivityViewController to share items from your iOS app is a simple enough task.

let activityVC = UIActivityViewController(activityItems: ["String to share"], applicationActivities: nil)
present(activityVC, animated: true, completion: nil)

Presenting UIActivityViewContoller modally works wells on iPhone:

However this results in a crash on iPad:

*** Terminating app due to uncaught exception ‘NSGenericException’, reason: ‘Your application has presented a UIActivityViewController (<UIActivityViewController: 0x7f829b854600>). In its current trait environment, the modalPresentationStyle of a UIActivityViewController with this style is UIModalPresentationPopover. You must provide location information for this popover through the view controller’s popoverPresentationController. You must provide either a sourceView and sourceRect or a barButtonItem. If this information is not known when you present the view controller, you may provide it in the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.’

The error message is self explanatory. UIActivityViewController is presented in a popover on iPad. Even documentations mentions this

On iPad, you must present the view controller in a popover.

Therefore, on iPad, you must configure `popoverPresentationController` by providing either a sourceView and sourceRect or a barButtonItem.

let activityVC = UIActivityViewController(activityItems: ["String to share"], applicationActivities: nil)
present(activityVC, animated: true, completion: nil)
if let popOver = activityVC.popoverPresentationController {
  popOver.sourceView = self.view
  //popOver.sourceRect = 
  //popOver.barButtonItem
}