Background view freezes after opening the share view

Question

So I have an app and a share extension. For the share extension I have just one simple controller that extends UIViewController and not SLComposeServiceViewController (I believe the default view is too complicated for what I am trying to do). What i'm trying to achieve inside the extension is to get some data from UserDefaults, make some HTTP requests and show an alert with the HTTP response. The share extension should only be used inside a browser, but after I tap the extension the browser view freezes and after I dismiss the alert the browser is still frozen. How and where I should dismiss the alert or the parent view?

I'm new to this environment but I did some research and I believe this has something to do with the view hierarchy but I'm not sure, here is the controller:

class ShareViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
}

override func viewWillAppear(_ animated: Bool) {

}

override func viewDidAppear(_ animated: Bool) {
    let alert = UIAlertController(title: "Notification", message: "message", preferredStyle: UIAlertControllerStyle.alert)
    alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))

    self.present(alert, animated: true, completion: nil)
  }
}

Answer 1

It's a duplicate and I'm not sure if I should answer here as well. Sorry for not searching enough. For swift 3:

self.extensionContext!.completeRequest(returningItems: nil, completionHandler: nil)