Display UIActivityViewController as form sheet on iPad

Question

I'm trying to display a share sheet without using a popover, ie no source view, or arrow.

Here's my code, starting from a base, single view app:

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    @IBAction func didTapShare(_ sender: UIButton) {
        let activity = UIActivityViewController(activityItems: ["banana"], applicationActivities: nil)
        
        if UIDevice.current.userInterfaceIdiom == .pad {
            activity.modalPresentationStyle = .formSheet
//            activity.preferredContentSize = CGSize(width: 400, height: 400)
        }
        
        present(activity, animated: true, completion: nil)
    }
    
}

This is of course crashing

"UIPopoverPresentationController (<UIPopoverPresentationController: 0x7fce07507900>) should have a non-nil sourceView or barButtonItem set before the presentation occurs."

But I don't want it to look like a popup, or have an arrow -- I want it to appear as a form sheet, in the middle of the screen.

Here's how it look in the Photos app:

Answer 1

If you don't want to display UIActivityViewController as popover but rather as formSheet or pageSheet, you can just create your own view controller with UIActivityViewController as its child.

class ShareSheetController: UIViewController {

    private let activityController: UIActivityViewController

    init(items: [Any]) {
        self.activityController = UIActivityViewController(activityItems: items, applicationActivities: nil)
    
        super.init(nibName: nil, bundle: nil)
    
        modalPresentationStyle = .formSheet // or pageSheet
    }

    required init?(coder: NSCoder) {
        fatalError()
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    
        addChild(activityController)
        view.addSubview(activityController.view)

        activityController.view.translatesAutoresizingMaskIntoConstraints = false
    
        NSLayoutConstraint.activate([
            activityController.view.topAnchor.constraint(equalTo: view.topAnchor),
            activityController.view.bottomAnchor.constraint(equalTo: view.bottomAnchor),
            activityController.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            activityController.view.trailingAnchor.constraint(equalTo: view.trailingAnchor)
        ])
    }

}

Then you can present the ShareSheetController just like any other view controller.

let shareController = ShareSheetController(items: ["some_text"])
present(shareController, animated: true)