Invalid resource directory CocoaTouch framework

I'm trying to compile a basic Cocoa Touch framework to test this new feature in iOS 8 but I'm encountering some problems. First of all the framework doesn't import any other frameworks or libraries and the deployment target is set to iOS 8 (regular project when trying to create an Cocoa Touch framework. I added two methods:<br />
- addValue:toValue<br />
- subtractValue:fromValue
<br /><br />

Compiling the framework goes without any problems as long as I'm not trying to code sign it. When I import the framework in my TestFramework project and I press build I getting this as build result:
I'm running into a peculiar error which doesn't seem to affect anyone on the web because nobody has complained about this error yet. The error is as following:


Warning: usage of --preserve-metadata with option "resource-rules" (deprecated in Mac OS X >= 10.10)!
.../DerivedData/TestFramework-ethagmafcjzncuftipguwzdeiezh/Build/Products/Debug-iphoneos/TestFramework.app/Frameworks/BasicFramework.framework: replacing existing signature
.../DerivedData/TestFramework-ethagmafcjzncuftipguwzdeiezh/Build/Products/Debug-iphoneos/TestFramework.app/Frameworks/BasicFramework.framework: invalid resource directory (directory or signature have been modified)

I mentioned that this "invalid resource directory" is an known issue for MAC developers but I can't seem to find the right solution. Who can point me in the right direction?

EDIT: I found out that it definitely has something to do with the code signing. Probably I need to code sign the framework too but that's not possible because I encounter the same error.