I've been working on an experimental tool for real-time design of iOS apps called Lightning (http://getlightningapp.com).
Lightning is a Mac app that brings iOS inside the design canvas. The idea is to design directly on top of iOS, so you use real iOS controls, feed it with data and edit it in real time.
- Real iOS controls using Apple's native animations
- Easily integrate data into your design. Change your data and see your design adapt in real time
- Add and modify logic directly on the canvas, while your app is running for instant feedback
- Use platform constraints to guide your design decisions
You're always editing a real iOS app, so there are no approximations. You can check it out here
Would love to hear what you all think!