iPhone & iPad User Interface Design: Mimic the real world

In iPad and iPhone design, you have to remember that everything wants to be touched. Anything that is touched needs to be instantaneously responsive. If it is not responsive, then it just won't feel right. There needs to be feedback, and it needs to feel rich, quick and real. Feedback is one of the most important elements of user interface design, and can come in the form of sounds, alerts, text messages, and animations.

As a developer, you should strive to mimic the real world. If you're creating an application that contains notes in a binder, consider using textures like black leather, steel rings, and white binder paper. If there is text on the paper that can be erased, consider showing eraser residue until the user is done pressing the back button on the device. If you're on the iPad, then each finger swipe to go to the next page can actually look like you're flipping a real page in a book.

Now don't let the feedback mechanisms, like animation, get in the way of the usability of your application. Animations, for example, need not be gratuitous. You should find the right balance between interesting, meaningful, and appropriate when using animations. Moreover, try to prevent the user from typing wherever possible. If you know the user's location, don't make them type it in. Make your users pick from a list instead of forcing them to type. This will make your user's life easier.

Lastly, iterate on your UI and ask yourself "how can I make this better?" You may think that you've completed most of the UI in your application, and it all feels right. However, you may add another feature, which will no longer cooperate with your existing UI. In this case, you'll have to hit the drawing board again, but as painful as that is, it keeps your application from becoming stale!