As you know, I'm spending 5 months working remotely for ReignDesign. Because I've been staying in various hotels, rather than carrying my house key I generally have a hotel key-card in my pocket. It's a simple but clever design: the typical keycard opens the door, and activates the electricity when the card is placed in the holder by the door. What are the advantages of a keycard... and how did this get me thinking about mobile apps?
1. Doesn't matter if you lose the card, the hotel can cancel it and issue you another
If you lose a physical key, you'd generally need to change the locks, as the key could have fallen into the wrong hands. Moreover, a guest could get another copy of the key cut, and use it to break into the room later. By using a card as a "token" of your access rights to the room, the hotel has more control. If you lose the card, the access rights of the old card can be cancelled, and a new one issued.
You should bear this lesson in mind when implementing any kind of authentication for an app. A naive authentication scheme (like HTTP Basic Authentication) might send username and password with every request. By contrast, a more advanced token-based authentication scheme like OAuth will exchange your credentials for a token (the equivalent of a keycard) which is of less use if intercepted.
2. Saves electricity, because you can't leave the lights/air conditioner running when you leave
Particularly in a room you're not familiar with, it's easy to accidentally (or lazily) leave lights or electrical appliances on. The keycard effectively collapses a series of actions: turn off the lights, switch off the heater, find the keys, lock the door... into a single one: remove card.
Similarly, when users are using your app, they're using an information hierarchy they're not familiar with. This, combined with the limited screen size, means it's essential to collapse your information hierarchy into something very simple. What might work well as a 5-page wizard with various optional sections on a desktop computer would need to be simplified and linearised to work well on a mobile app.
3. The card is in an obvious place when you leave, so you don't lock yourself out
When I leave the hotel room, the card is right in my field of vision, so it's natural to take it as I leave. I'm much less likely to leave the room without the key.
Once people have been using a particular mobile device for a while, they gain certain spatial expectations about how the user interface will behave. For example, the standard position for an iPhone back button is in the top left. Many games place the back button in a different corner, for example bottom right. Be aware this will cause users to expend more mental energy when they're using the app. Unless there's a very strong reason not to, stick to standard placements for controls.
What other lessons have you learned from everyday objects? 🙂 Leave any ideas in the comments.