My iOS software enhancement wishlist is pretty long. Off the top of my head I can think of: some form of inter-app communication, an easier way to change brightness (or more functional automatic brightness adjustment), allowing minor updates without requiring a restart, and of course some solution to the iCloud/document siloing problem. But the iPhone enhancement I really want is faster app-switching, which I think can only be satisfactorily solved with a hardware modification.

App-switching is inherently a power-user feature. Grandma really shouldn’t need to task switch, just like she probably doesn’t even need to know how to copy and paste. The built-in sharing features should be able to capture her use cases. Even casual users will only need to task switch every once and a while. I bet a lot of iPhone users don’t even know they can double-tap the home button, instead falling back on pressing the home button and selecting the second app from the home screen. Power users, however, want to switch apps all the time. They may be doing research in one app and writing in another, or reading in one app and chatting in another. For them, the home button double-tap is cumbersome and annoying.

The iPad elegantly solves the fast app-switching problem with a four finger swipe. Because the friction of moving from one app to another is substantially decreased, this feature enables streamlined new workflows. A lot of iPad users probably don’t know about this feature. For them, the home button is still available. I would compare this to how most people might not know about Command-Tab app-switching on the desktop, but how power-users who want that speed depend on it.

I’ve seen mock-ups and hacks on jailbroken iPhones trying to improve the app-switching experience. Some of them have small app previews, which are nice but don’t solve the speed problem. Others use swipes in from the side of the screen, which I think is confusing (it’s likely to be triggered by accident) and steals another gesture from app developers. The swipe from the top has already been stolen by the notification center, if swipes from the left and right are taken, too, then it really limits the utility of the swipe gesture for app developers, not to mention confusing users.

With screen gestures we’re too limited in space on the iPhone. Multi-finger swipes take too much room. Therefore, I think the best way to solve this problem is with hardware. I propose taking the home button and widening it by about a half centimeter on both sides (it might look something like this old mock-up)

This expanded home button will be touch sensitive across its whole surface, but it will also be a button across its whole surface. Apple already has a design similar to this: the trackpads on all its laptops. Now, add one gesture to this home button: swiping left and right moves between apps (optionally, you might add a second, two-finger gesture to bring up the home panel).

Because the button still acts as a button, we keep all of the advantages of a single button smartphone. It still acts as an escape hatch. People who don’t know you can swipe on the button don’t have to. It’s not a required interaction because the old style app-switching (press home, reselect from home screen) is still there. The swipe gesture is easy to recognize and not easily confused with a button press gesture, so it doesn’t interfere with the standard home button usage. With it, though, app-switching becomes a one swipe operation, making the phone feel a lot faster, and the use of multiple apps a lot more enjoyable.

With this simple enhancement, Apple would please the power-users while still maintaining it’s famed ease-of-use for beginners.