iPhone App de-listing may be mysterious process that takes place behind an opaque curtain of mystery, but TUAW discovered that the approval process is just as undecipherable. Two developers contacted them recently to fill them in on why their apps were rejected, one of which-rejected because they used vibration in a game-seems pretty ludicrous to us.
There's supposedly some unwritten rule among app developers that you're not supposed to use the phone's vibration feature for anything but alerts, not game enhancements. That's right. No force feedback when your race car hits a wall or when your avatar takes a blow to the face. Seems quite arbitrary to us, seeing as most people should be able to figure out that a vibration in a game comes from the game itself, not from an SMS message that didn't also pop up a visual notification.
The second was from another developer who didn't follow Apple's design conventions and put a toolbar at the top of the screen instead of the bottom (yeah, notice how all your apps have the toolbar at the bottom?). Not only that, they didn't change the shade or color or icon of any of the entries on the toolbar to allow the user to see which one was selected, which is a bad design decision if we've ever seen one. Not too bad that this one's rejected.
We're sure there are a few more unwritten rules of iPhone development that we don't know about, so if you're a developer that's been rejected for some reason, drop us a note at email@example.com. [TUAW]Update: Jonathan points out that the force feedback rule could be to avoid paying the patent on rumbling controllers that all the major console makers had to dish out on. Most recently (and notably) seen on Sony's PS3.