Now that I’ve covered some of the technical issues with background processing for iPhone applications, let’s take a look at why it’s a bad idea from the user’s point-of-view.
Assume that Apple changes their mind about background processing tomorrow–anyone can do whatever they want in the background. All the naysayers rejoice, and in a year’s time they’ll be asking Apple to remove background processing.
Why? Same reason as always. The iPhone requires a fundamentally different approach to user interaction. Something that goes way beyond the obvious things like the multi-touch interface.
If you can have a background process running on your iPhone, what is that process going to do when it detects a state change? What happens with a buddy comes online, or a new piece of data is available, or when a long running calculation is completed?
You’re going to want to notify the user, right? Again, “desktop thinking” makes this sound like a simple thing. But it’s not.
The iPhone is going to attract network aware applications like moths to a flame. In a year’s time there will be hundreds, if not thousands, of applications using the Wi-Fi and EDGE connections. You’ll likely have several of them on your iPhone: let’s say you have five.
You now have five independent sources for notifications. How do you let the user know which one is which? One might say, “make the sound different.” Another might say, “make something flash in the status bar.” Someone else might say, “make the phone vibrate.” Or even, “put up an alert box.” A truly sick individual might say, “Do all four.”
Can you see where I’m going with this? Your phone soon becomes a fricken’ pinball machine as multiple applications fight for your attention. With 24 notification permutations for every application, things will quickly get out of hand.
The desktop has evolved several mechanisms for notification: bouncing Dock icons, bezel windows, menubar icons, and things like Growl. These mechanisms all work together because they can share a common screen without unduly overloading the user.
But on the iPhone, you have a limited area and associated mechanisms for getting the user’s attention. In effect, it creates a notification bottleneck.
This notification bottleneck forces the user to work when figuring out who needs attention. First they have to recognize the notification by sound, feel or sight (or a combination of those senses.) Then they have to navigate to the recognized application, which may not be easy given the phone’s current state. Finally they need to deal with the source of the notification. Now imagine doing all this frequently: the network will end up being a constant source of distraction.
If you’re still unconvinced, let me ask you one final question: do you want to get IM notifications while you’re making a 911 call?