GPL Enforcement in Apple’s App Store/Android Market Place
So it seems that using GPL licensed software for iOS apps distributed on the Apple App Store (and yes, there are “other ways” to distribute software for the iOS-ish platform ;-)) is a problem…
“The problem isn’t in the license terms. The problem is that the Apple App Store ToS for people wanting to distribute through it require that each app sold (even at price zero) must be licensed for use on a single device only. Permissively-licensed FOSS can be transacted for in the App Store, because its license can be replaced by single- device-only terms. Copylefted software can’t be un-freely relicensed, so it can’t be transacted for there under Apple’s current ToS.”
The Free Software Foundation confirms this situation, as can be understood from this post on their website about GNU Go on iOS :
“An iPhone port of GNU Go is currently being distributed through Apple’s App Store. However, this distribution is not in compliance with the GNU GPL. The primary problem is that Apple imposes numerous legal restrictions on use and distribution of GNU Go through the iTunes Store Terms of Service, which is forbidden by section 6 of GPLv2. So today we have written to Apple and asked them to come into compliance. We would be happy to see Apple distribute these programs under the GPL’s terms, but unfortunately, it seems much more likely that they’ll simply make the problem go away by removing GNU Go from the App Store.“
An interesting question is: “What about Android?”
According to Moglen, if you want to distribute your GPL-software on Android, you should be in the clear:
“So far as we know–and we have reviewed the Google Android market terms recently, so change would have to have occurred within the last few weeks–they do not place any limitation on how a market participant’s application is licensed that would inhibit distributing Android applications in the market under copyleft licensing.”
So, according to various specialists, the Android Market provides some flexibility of its terms in what regards app distribution, which when carefully tuned, allows compliance with the GPL (contrary to Apple App Store, which has zero flexibility on their ToS).
An interesting point to note regards Dual Licensed GPL software (as is the case of Marsyas). In such cases, a developer may acquire a commercial license of the software (freeing it from the GPL license terms) and therefore use it for commercial use (without being obliged to distribute any source code) or develop an iOS app and distribute it on the Apple App Store (even as a free app).