UIActivityViewController completion handler returns success when tweet has failed

Use completion handler like this For SWIFT 3 AND 4, iOS 10 AND 11 :

activityVC.completionWithItemsHandler = {(activityType: UIActivityType?, completed: Bool, returnedItems: [Any]?, error: Error?) in
    if !completed {
        // User canceled 
        return
    }
    // User completed activity
}

self.present(activityVC, animated: true, completion: nil)