User interface designers usually work on desktop computers; they use tools like Omnigraffle, Visio, Adobe CS, or even Powerpoint to produce screen specifications and interaction flows.
A year ago, I had a chance to try Surface, the huge and innovative multi-touch table from Microsoft. I thought that would be fantastic to have UI design tools on a device like that. Imagine: just drag and drop interface components with your 10 fingers, assemble, resize and align them, swap two buttons in a spin gesture, in the most natural way.
I don't know if anyone made that for Surface, but there are some similar tools emerging for iPad and iPhone. I was much intrigued and tried a tool called Interface, for the iPhone (picture below).
Note: this product does not claim to be a design tool as such, just a handy application to quickly compose realistic screens directly on the device. However the test was enough to make obvious several issues that would apply to more sophisticated design products as well.
What I realised:
- Your finger - no offense - is too big: it hides the element you're manipulating, making adjustments harder. Just try to reposition the tiny information icon on the example shown above (bottom right). Also, the finger lacks accuracy for fine-grain operations. Some auto-snap functions help a bit, but it still feels like having to put a thread through the eye of the needle, you know what I mean.
- You need keyboard shortcuts: amazing how much you can get done thanks to them. Experienced users can invoke most of the controls instinctively, just by pressing a key combination. Hard to beat a method that is already at reflex level...
- You need space: the screen you design on must be larger than the screen you design for. Because you want your toolbars and building blocks library visible at all times around the working area. If you're not using keyboard shortcuts, you want to be able to spot your options in a second, in a toolbar at hand. Now if you are to design screen transitions (not just structure), then needless to say you need a LOT of space to manipulate and preview the whole diagram.
Now I'd like to see how a hybrid system would feel: it would let you do the high-level manipulation with the fingers (such as zoom in/out), and accurate things with a more traditional pointing device.
See also iPad versions of Interface (by Less Code) and Omnigraffle (by The Omni Group).