title: Swift & NSUserNotification - No banner or alert, but is silently added to the notification list
body: <p>I am learning Swift and wanted to display a simple user notification as a test.<br>
  My build is successful, but no banner is shown, instead, the notification is silently added to the list of notifications. I have verified 'Do Not Disturb' is off, I tried the same in AppleScript, successfully and once when fiddling around with <code>NSUserNotificationAlertStyle</code> and the code in the info.plist of my application, I got a successful, non-silent alert (not a banner).<br>
  However, this only happened once.</p>
  
  <p>I have created a new project, with Swift files and without storyboards. My AppDelegate.swift contains</p>
  
  <pre><code>import Cocoa
  
  class AppDelegate: NSObject, NSApplicationDelegate {
  
      @IBOutlet weak var window: NSWindow!
  
  
      func applicationDidFinishLaunching(aNotification: NSNotification?) {
          var notification:NSUserNotification = NSUserNotification()
          notification.title = "Title"
          notification.subtitle = "Subtitle"
          notification.informativeText = "Informative text"
  
          notification.soundName = NSUserNotificationDefaultSoundName
  
          notification.deliveryDate = NSDate(timeIntervalSinceNow: 5)
          var notificationcenter:NSUserNotificationCenter = NSUserNotificationCenter.defaultUserNotificationCenter()
          if let notificationCenter = NSUserNotificationCenter.defaultUserNotificationCenter() {
              notificationcenter.scheduleNotification(notification)
          }
      }
  
      func applicationWillTerminate(aNotification: NSNotification?) {
          // Insert code here to tear down your application
      }
  
  
  }
  </code></pre>
  
  <p>And my info.plist does not contain the <code>NSUserNotificationAlertStyle</code> mentioned earlier, for this shouldn't be necessary for banners, I believe.</p>
  
  <p>Lastly, yes, application "test" (for that's what I've named it) is set to show banners, as such.
  <img src="https://i.stack.imgur.com/x7EjA.png" alt="screenshot of Notifications System Panel"><br>
  Summarised: My application successfully makes notifications, and these will be added to the list of notifications, but not shown as a banner.
  (I am using OS X Yosemite 10.10. I hope this issue has nothing to do with the beta)</p>