launch containing app from iOS8 Custom Keyboard

I want to launch my containing app.

I tried using URL schemes.

The URL scheme launched the app from other places - so the problem is not there.

Looks like this object is nil:

   self.extensionContext

thus i can't run this method:

[self.extensionContext openURL:url completionHandler:nil];

Can I launch my app? Do URL Schemes work in a custom keyboard?

thanks!