I'm not sure if this has been mentioned before, but there really is a certain order in the chaos of Apple's iPhone icons. Well, at least there used to be up until the iPod touch...

What i'm talking about is color coding - if you take a closer look, you'll notice that, i.e., phone-related apps have green background (SMS, Phone), apps that require internet connection or rely on internet services have a blue background (Mail, Safari, Stocks, Weather), while apps and widgets that can be represented by physical objects don't have a background at all (Calendar, Camera, YouTube, Maps...).

The only exception to this logic, as far as Apple's native apps are concerned, is the Photos app. Logic would suggest an orange background, just like the iPod's, as it's a part of iPhone's "multimedia suite". Instead, it depicts an orange sunflower on a blue background.

The point of my post is this - wouldn't it be neat to extend the same visual language to the third party apps as well? Icons for them are extremely chaotical in appearance and most of them don't really convey their application's content, function or purpose at a first glance.

For example, Books.app has an orange background - the first thing i think when i see it scrolling up the screen is - oh look, it's a multimedia app. Which it isn't. Then there's Apollo, with it's black, spacey background that doesn't mean anything at all and actually makes the icon less noticable on a black background. Or weDict, whose blue background would suggest an internet connection or a web based app at a first glance. Or MobileChat, that has an icon mimicing SMS.app's, but with an orange background, suggesting it does the same thing as SMS.app, but clashing with the iPod icon's color (it really should be blue to be consistent with the original UI language).

I'm not trying to say all the icons suck or that they aren't pretty enough. I'm talking about usability and UI guidelines here. I'm also not trying to tell none of the third party apps have nailed it with their icons, as there are plenty of good examples too - Installer has a rightly chosen blue background, although at a slightly different hue than Apple's own blue icons; ToDo nails it right with an icon modeled after Calendar's, that clearly associates it with it as a part of a PIM application set; Sketches also does it right, with an icon depicting a physical object (etch-a-sketch) etc.

What i'm trying to say is, maybe it would be a good idea to start a serious UI guideline wiki of some sort that'd serve as an anchor point for the design of future 3rd party apps and "enforce" (in the most gentle sense) some uniformity to their UI design. What'cha all think?

+1 from me for this good idea!