>You are perfectly free to distribute the source code to an app you publish to the App Store.
But the GPL states that when a user receives a binary, they may request the complete corresponding source code to that software. That doesn't mean most of the code, minus this proprietary bit that handles DRM.
By that reasoning, you couldn't use any compiled GPL software on Windows, either, since the code will be linked with Microsoft's runtime libraries (which are decidedly not FOSS).
But the GPL states that when a user receives a binary, they may request the complete corresponding source code to that software. That doesn't mean most of the code, minus this proprietary bit that handles DRM.