For the project I\'m working on I needed to unzip certain files. For this, I found the library SSZipArchive. I included this in Xcode 4.2 (Right-click on the Classes folder->Add
After a lot of headaches, I figured out what was the problem. It turned out to be _Prefix.pch. I totally looked over it, but it turns out that I had the following line there:
#import "someclass.h"
This class was being loaded in with the .c-files of the minizip library, resulting in Objective-C headers being included in .c-files, which was something that XCode did not like. Wrapping these statements in an #ifdef statement fixed the problem:
#ifdef __OBJC__
#import "someclass.h"
#endif