“What did you just do?”
4 fingers swipe across the screen, and it switches to the next app.
People know astonishingly little about the basic gestures on iOS, even this many years after the iPhone's release. The average person on iOS knows only the most obvious, scrolling up and down with a movement of the fingertip, swiping sideways to turn a page (but if obviously applicable) and if we’re lucky, the slide right-to-left to delete.
Did you know in some apps, tapping the header returns you to the top of the page? Twitter's app did, in 2010. They designed their app to scroll directly to the top of the page when you tapped the header - and so few people used the feature that they removed it.
Check out the Bing page for "iPhone Gestures":
- Five Secret iOS Gestures You Need to Know
- Learn All the iPhone Gestures Here
- Top 5 Secret Gesture Tips
- ... and many more!
Implementing these gestures would make your app that much more awesome, because it would hide menu buttons and make the interface cleaner, right?
If you didn't even know about half these gestures (which statistically, you probably don't) you can't expect your users to know the features either.
You need to be conscious of your new users (the non-tech users), who don’t know the gestures and probably won’t ever take the time to learn them. There are gestures beyond the ones with an obvious physical metaphor, but most people won't ever learn them.
The book Tapworthy by Josh Clark accuses many people of not even knowing the pinch-to-zoom gesture, and it’s saddening to believe. This means that your fantasies of users navigating your brilliant iPhone app with simple swipes, like a god manipulating his Sim City, will not come to fruition.
Most people alive are too used to the mouse-computer metaphor to adopt fancy or complicated gestures, and those that aren’t are barely entering high school. Unless your app is designed for those individuals, please listen in.
Don’t hide features of your app in a rotating or multi-touch gesture, because there is a plethora of people who will miss it. An easter egg in a game being hidden in a multi-touch gesture would be cool, but in anything but a game people will miss the feature and then miss out on the value they could have had.
You can include gestures, but make sure people see the physical metaphor for what they’re doing. To swipe, you need to be prompted by the sight of a page. For more complicated gestures, if you don’t explicitly tell a user what to do upon opening the app or provide an alternate visually-based way of performing the action, it will simply be lost on the user.
A lot of apps take the hybrid route of including the more complicated gestures for the power user but still provide a seamless visual way to do something for the casual users.
For the gestures that people do use, you need to be careful not to 're-write' what a gesture means in their head. For instance, swiping down from the top of the screen brings down the notification center; creating a conflicting gesture will both confuse the iPhone on input and confuse the user of the app. Here is an [incomplete] list of currently-used specific gestures:
- Swiping down from the top: This brings down the notification center.
- Sliding an element: This shows the delete button, a very common feature people expect to see in apps.
- Shake: shaking the device is to undo or redo an action, a gesture people don't usually think of.
You can get full descriptions of the common gestures here.
People are already natively familiar with the pinch, tap, and rotating of the iPhone, if not from personal use then from seeing a commercial. A more complete list of gestures can be found in the iOS Human Interface Guidelines online, although even the HIG does not go over all of the gestures actually available on the iPhone.
As per usual, all this warning you about gestures should be taken with a grain of salt; The most unique iOS apps have used common gestures in a new and interesting way that remained useful after the novelty wore off. If people can jump into your app and understand your unique and new gestures intuitively, you have design gold on your hands.