Both versions of the GPL have an exception to their copyleft, commonly called the system library exception. If the GPL-incompatible libraries you want to use meet the criteria for a system library, then you don't have to do anything special to use them; the requirement to distribute source code for the whole program does not include those libraries, even if you distribute a linked executable containing them.
- https://www.gnu.org/licenses/gpl-faq.html#SystemLibraryExcep...
But I think it would be easier just to not have apps covered under the appstore license, and only add such license to their own DRM. How effective the legal DRM would be in that case could be discussed, but it would likely identical to consoles and tivo which are both gplv2 compatible. It seems unnecessary when looking at other products with DRM to have a license that cover every program running on them.
It feels wrong to deny users access to GPL software because of terms of service applying to the underlying OS. As long as the software itself is available in source form under the GPL (either packaged inside the .ipa, and/or with a link to a page where you can download the source under GPL with no EULA attached) should afford the user all the freedoms of the GPL.
But I guess smarter people than me have decided this is unacceptable, so users can't be allowed the convenience of pre-compiled iOS GPL software?