In swift, if you instantiate the view controller from the storyboard identifier, you typically need to cast it. However, since the storyboard identifier is typically the same as the vc name, it might be perfectly acceptable to just pass in the type and convert that to a string. Since you passed in a type, the function can infer the return type.

TypeInferedVCFromStoryboard

extension UIStoryboard {
    func instantiateViewControllerWithTypeAsIdentifier<T>(t: T.Type) -> T {
        return instantiateViewControllerWithIdentifier(String(t)) as! T
    }
}