Setting an identifier for an Xcode Storyboard Segue in a UITabBarController, and getting a pointer to its view controller

This is my first app using storyboards/segues, and I'm pretty sure the answer to this is easy, but I'll be as thorough as possible in describing my issue. I am making a simple app which has a Tab Bar Controller scene and two View Controllers. My app launches by being sent a URL from another app. The `application:openURL:sourceApplication:annotation:` method in the app delegate performs some work to determine - which tab to display first, and - what information to display on it. My goal is to use the `performSegueWithIdentifier` method (I'm open to alternatives though) from within the AppDelegate to select the tab, and also find a way to send a method to the instance of the view controller created by the storyboard. Issue #1 is that I can't set an identifier. When I select the tab "relationship" there are no choices available in the Attributes Inspector (it says "Not Applicable"). How do I set a name for this segue? Can I? Or is there some rule under which UITabBarController segues can't be trigger programmatically? Issue #2 is that I can't find a way to have a pointer to the view controller. Pre-Storyboard I would `alloc` and `init` a new view controller and then set it up, but here if I do that, it does not get displayed when my app launches (I think this is because Storyboard is displaying a different instance of the same view controller.) I know this post is long, but I feel like I'm missing something simple. What is it?