Hack gives iPhone Developers Access to Dynamic Launch Images

November 2009

Disclaimer

Sun	Mon	Tue	Wed	Thu	Fri	Sat
1	2	3	4	5	6	7
8	9	10	11	12	13	14
15	16	17	18	19	20	21
22	23	24	25	26	27	28
29	30

This website is not owned by, is not licensed by nor is a subsidiary of Apple Computer, Inc. Apple iPhone are trademarks of Apple Computer, Inc., registered in the U.S. and other countries. The content of this website is not supplied or reviewed by Apple Computer, Inc. All articles, images, logos and trademarks in this site are property of their respective owners. Please follow this link to read the complete disclaimer.

Developer Patrick Collison has published a technique which tricks iPhone’s code signing mechanisms into giving third party iPhone developers access to dynamic launch images rather than being stuck with static ‘Default.png’ images.

Jason Kincaid of TechCrunch had initially believed that it was a serious security flaw as he felt developers could use it to bypass Apple's App Store approval process to release an updated version of their iPhone app by executing arbitrary code from within their own applications whenever they wish.

But has later clarified that it is not as serious as he had initially thought but it is a legitimate bug.

Whenever you launch an iPhone app, an image called ‘Default.png’ is briefly displayed (more or less as a title card for the app) while the app loads in the background.

As of now, the iPhone apps developed by Apple are able to use dynamic images while third party iPhone developers have been stuck with static ‘Default.png’ images.

The dynamic images gives Apple the flexibility to overwrite the default.png file with a screenshot of the iPhone app when you quit it. So when you launch that app again, you will immediately see the screenshot while the app loads in the background giving you a feeling that the app has launched instantly. As the third party developers don't have access to dynamic images the behavior of the their apps is not as smooth as the apps developed by Apple.

Jason Kincaid of TechCrunch had initially believed that it was a serious security flaw as he felt it could be used as an exploit to update and execute arbitrary code regardless of content whenever the developer chooses to do so. Some experienced iPhone developers also seemed to agree with Jason's analysis. However he has later clarified that "it not as serious an issue as we thought - while it is a legitimate bug".

Patrick also believes that his trick is possible because of a bug and is guessing that Apple will fix it in some future version of iPhone firmware.

If you are interested in checking out the technique posted by Patrick, you can download an Xcode Project demoing the trick and can also watch the video on Patrick's blog.

Follow this blog