@IBAction func shareTextButton(_ sender: UIButton) {
// image to share
let link = "https://www.google.rs/"
// set up activity view controller
let activityViewController = UIActivityViewController(activityItems: [link], applicationActivities: nil)
activityViewController.popoverPresentationController?.sourceView = self.view // so that iPads won't crash
// exclude some activity types from the list (optional)
activityViewController.excludedActivityTypes = [ UIActivityType.airDrop, UIActivityType.postToFacebook ]
// present the view controller
self.present(activityViewController, animated: true, completion: nil)
}