I wonder if there is any tool that can be used to develop the app design (like Justinmind's Prototyper program) and then export to xib or storyboard format.
I wonder if there is any tool that can be used to develop the app design (like Justinmind's Prototyper program) and then export to xib or storyboard format.
I do not think it exists, and I see no reason to exist something like that. The storyboard is not a design tool like photoshop, or an extension as a jpg. It is part of an architecture called MVC.
The XIB / Storyboard as the "VIEW" of MVC, has several responsibilities like: create link between view and controller, offer ways to make your view adaptable to portrait and landscape using Auto Layout, you can insert things in your view through code, and in XCode 6, you only have 1 storyboard for phone, tablet and desktop. Mounting the view of your application is not something that can be generated, it should be developed.
What converts does not, but has Sympli that helps you create the Sketch layout for xcode