Zitat:Cached .artwork Themes
Finally, the most complex example of image-based themes I've so far seen has to do with .artwork files. These files exist as loading lots of small .png files from disk can be irritatingly time consuming, so instead they are loaded as block and stored (I believe) in a shared memory cache. As these tiny graphics are often used to build all aspects of the interface these represent the ultia thule of iPhone theming.
Messing with them, though, is currently really hard: you have to use special tools to unpack the files and all you get out of them are a bunch of numerically-named png files (.artwork files don't have filenames in them). You then have to carefully make new images of the same size and rebuild the complete .artwork file, which then has to be installed on the phone with a rickety package that attempts to backup and restore the original. Yeek!
After I heard about this, I set out to fix this with WinterBoard: I want theming to be a fun, safe experience that can be taken up by anybody without special tools. To do this I first analyzed how .artwork files worked, and lo and behold there actually are filenames that go with all of those png files people were compressing (already this makes the task a million times easier.
At first I implemented this by providing a folder in your theme called UIImages/ in which you can store replacements for these files. As an example, you might have UIImages/UISearchFieldIcon.png (which happens to be the name of the little magnifying glass used at the left of text fields to indicate you can search with them).
However, I have since figured out that these .artwork files are actually designed to be a cache of files that are otherwise part of a bundle and should really be stored in Folders/UIKit.framework/. The UIImages/ path will be maintained for backwards compatibility. This new understanding, combined with some code updates, means that we can now theme any .artwork file (such as those used for MobilePhone.app).
I'm writing this documentation a little bit before the WinterBoard release related to it, so for right now you need to keep using UIImages/. The support for MobilePhone.app is in there, but hooking back to UIKit.framework/ is not.
Of course, you need to know what you can put there to make this feature useful. For a list of filenames you can theme you can grab this text file, but just having the names isn't really helpful. While I currently feel uncomfortable distributing a copy of these images from Apple as a file on my website, I have released a tool as part of WinterBoard that will let you quickly extract them for yourself called, yep, UIImages. Here's how you use it:
mkdir /tmp/images
cd /tmp/images
/Applications/WinterBoard.app/UIImages
ls UISearchFieldIcon.png -la -rw-r--r-- 1 root wheel 468 Aug 4 03:13 UISearchFieldIcon.png
One final variant are things that are loaded from a "mapped image domain". Common examples of this are the TextInput localization bundles. The way you specify these is using Domains/TextInput_ru/std-kb-ru.png.
