Swift: Set UIBarButtonItem as source for popover WITHOUT tap?

Question

I want to show a popover on iPad as soon as my view loads having as source a button on the top right corner. The popover displays properly on button tap, but I'm having trouble finding a way to display it without the button tap, when the page first loads. Is this possible?

This is what I have:

func displayOptions(sourceButton: UIBarButtonItem)
    let actionSheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
    if let popoverController = actionSheet.popoverPresentationController {
        var rect = CGRect(x: 0, y: 0, width: 0, height: 0)              
        popoverController.barButtonItem = sourceButton              
        popoverController.sourceRect = rect 
        popoverController.permittedArrowDirections = .up
    }
    viewController.present(actionSheet, animated: true, completion: nil)
}

This code works properly on button tap, but the app crashes if I try to call this function from viewDidLoad or viewDidAppear:

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.

Answer 1

1. You need to provide the sourceView.

2. UIAlertController must have a title, a message or an action to display.

   // Create a bar button item in ViewDidLoad.
   let button1 = UIBarButtonItem(image: UIImage(named: "imagename"), style: .plain, target: self, action: Selector("action"))
   self.navigationItem.rightBarButtonItem  = button1
   
   
   // Call in ViewDidLoad
   displayOptions(sourceButton: button1)
   
   func displayOptions(sourceButton: UIBarButtonItem) {
       let actionSheet = UIAlertController(title: "title", message: "message", preferredStyle: .actionSheet)
       if let popoverController = actionSheet.popoverPresentationController {
         let rect = CGRect(x: 0, y: 0, width: 0, height: 0)
         popoverController.barButtonItem = sourceButton
         popoverController.sourceRect = rect
         popoverController.sourceView = self.view
         popoverController.permittedArrowDirections = .up
       }
       self.present(actionSheet, animated: true, completion: nil)
   }
   

Answer 2

Try using UIPopoverPresentationControllerDelegate

Code example:

• viewDidLoad

  let buttonCustom = UIBarButtonItem(title: "Custom", style: .done, target: self, action: #selector(ViewController.customBarButtonAction))
  self.navigationItem.rightBarButtonItem  = buttonCustom
  displayOptions()
  

• displayOptions

  func displayOptions() {
      let actionSheet = UIAlertController(title: "Title", message: "Message", preferredStyle: .actionSheet)
      if let popoverController = actionSheet.popoverPresentationController {
          let rect = CGRect(x: 0, y: 0, width: 0, height: 0)
          popoverController.sourceRect = rect
          popoverController.sourceView = self.view
          popoverController.permittedArrowDirections = .up
          popoverController.delegate = self
      }
      self.present(actionSheet, animated: true, completion: nil)
  }
  

• using UIPopoverPresentationControllerDelegate

  func prepareForPopoverPresentation(_ popoverPresentationController: UIPopoverPresentationController) {
      popoverPresentationController.barButtonItem = self.navigationItem.rightBarButtonItem
  }