1. 1 App = 1 Job

Think about one job you want to do for your user and do it well.

It’s possible for an app to have multiple tasks. But at its core a mobile iPhone application should do one job in its user’s life.

Remember, it’s better to do 1 thing great instead of 5 things just okay.

The iPhone clock is a stopwatch, an alarm, a world clock, and a timer – but time is its overall job.

2. Clarity Not Cool

Simplicity is the rule – coolness can come later.

Use visual metaphors and consistent controls. Help users adjust to new interfaces by creating digital versions of things they already know and like.

The mobile space is a fundamentally different space than the Web. Here we are dealing in limited real estate and limited bandwidth – not with an unlimited page with all-you-can-eat, piled-on features.

What are iPhone metaphors? Cards you can flip, pages you turn, dials and wheels you spin: these are controls users already understand. By integrating these into mobile experiences, it makes this transition feel fun and familiar.

3. Bite-Sized Snacks All Day Long

Mobile applications are short but deep experiences. They allow for little moments during the day to connect with things we like, breaking news, stock information, instant messages. Instant applications are the perfect companion in line at the bank, or on the subway, or anywhere when you have a few moments to yourself.

Remember, this is not Gone With the Wind. Be sure to put the things that people want to check all day long in prominent places with the least amount of wait time. Make the information quick, make it fun and keep it coming.

4. Instant Fun

Put regular experiences in a new space – to realize hidden fun potential.

New interfaces should be fun. When possible use the accelerometer, which allows the user to interact with the device using movement instead of just touch.

Emphasize action, not buttons.

Mobile Zodiac updates the classic daily horoscope with a touch wheel where users choose their sign and then adds contextual pictures to go along with the fortune.

5. Build Advertising into the DNA

Look for places where advertising can live in your applications. Mobile advertising engages the user when it promises fun just around the corner. Keep the information location-relevant and suddenly it has greater urgency.

This type of advertising creates better interfaces for customers to connect with advertisers.

And it makes it easy for advertisers to get deep metrics on user behavior. Advertisers learn who’s looking at what, where they saw it, when they saw it, and what they did after they saw it.

This location-based movie ad introduces the elements of time and place, culminating in a potential transaction.

6. Observe What Works

When in doubt, use the marketplace as a guide for what’s successful. Understand that the most successful products in the mobile space thus far have been:

• weather
• news
• sports
• games
• text messaging
• social networking

Users spend a lot of time checking these things throughout the day.

The most successful web applications on the iPhone so far are re-imaginings of classic Web ideas imported to fit this new platform. Look and learn from what already works; integrate features, interfaces, and concepts.

7. Make Every Server Call Count

Unlike the Web, mobile devices are not constantly connected to the Internet. Data is pushed in small packets. The more economical you can be with those connections, the better experience for your user – it will reduce download lag and save battery life.

To limit server calls, design apps that push the types of information – news, messages, ads – that will show just enough for users to get the gist, and will allow them to dig deeper if they desire more information.

Server calls are expensive and test the user’s patience. Good mobile apps push once rather than make many server calls.

8. Brands Matter

New mediums can be strange places. People are always more likely to try new things from brands they know and trust.

This is a place where familiar faces can be revitalized and seen through a new lens, a place where brand experiences get closer and go deeper.

9. Make Connections.

The iPhone enables brand transactions at the same time as it raises brand awareness.

The mobile space is a place where we can go from content to transaction without anything in-between – no phonebook, no website, no advertising outside the medium itself. There’s nothing between you and what you want, when you want it.

Instant enablement of brand promise in the space where brands live, in the world users live in – that’s how the iPhone brings users closer to brands.

10. Honor Thy User

People have quickly adopted the iPhone because it is so easy to use. In designing apps for mobile devices, ideas must not come at the expense of adoptability.

Limit the app to the essence of what it needs to do. Reduce anything superfluous, even if it’s cool.

The point of all of this is to make life easier for our users – to connect them with the news they want, to anticipate what information they will want to know, to offer a suite of experiences and fun ideas that are always just around the corner.

Apps should load fast. The experience should be quick and short. Apps should limit typing. They should not try to replace the functionality of the handset.

Our task is to do this in a way that is easy-to-use and intuitive.