Apple Mach-O linker (id) warning : building for MacOSX, but linking against dylib built for iOS

Sometimes it's easier to debug Xcode problems by looking at the build log for the command lines it's using.

If you're building from the command line, you can get that message if you don't specify -miphoneos-version-min=

This compiles:(where conftest.c just contains int main() {})/Applications/Xcode5.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch i386 --sysroot /Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.0.sdk --sysroot /Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.0.sdk -miphoneos-version-min=6.0 conftest.cAnd this gives the error:/Applications/Xcode5.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch i386 --sysroot /Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.0.sdk --sysroot /Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.0.sdk  conftest.cld: building for MacOSX, but linking against dylib built for iOS Simulator file '/Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.0.sdk/usr/lib/libSystem.dylib' for architecture i386clang: error: linker command failed with exit code 1 (use -v to see invocation)

Check your Framework Search Paths for your Main target and your test Target.

I had a lot of crap in mine.

had old project written in XCode 4 and just started to use Unit Tests in XCode 5.

Here's the minimum I have to get my test project to run

Project Navigator > click on project at top >Targets > Build Settings > Framework Search Paths

TARGET:my_project$(inherited)"$(SRCROOT)""$(SRCROOT)/my_project"TEST:my_projectTests"$(SDKROOT)/Developer/Library/Frameworks"    <<XCTest.framework is here"$(DEVELOPER_LIBRARY_DIR)/Frameworks""$(SRCROOT)/..""$(SRCROOT)"                             << Documents/my_project"$(SRCROOT)/my_project"                  << Documents/my_project/my_projectwhere directory structure isDocuments/my_project    my_project.xcodeproj    /my_project

Note: If you drag a framework into XCode. XCode 5 has bad habit of hardcoding the path

/Users/gbxc/Documents/my_project

should be

"$(SRCROOT)"                             << Documents/my_project"$(SRCROOT)/my_project"                  << Documents/my_project/my_project

so if you moved your project might get problems

Best way to check whats correct is to create a new single view project that runs tests ok.

Run the Test actionBy default it fails but at least testing is runningthen compare the  Framework Search Paths.

If you're using Carthage and compiling a Mac app, search on your project's Framework Search Paths you might find something like $(PROJECT_DIR)/Carthage/Build/iOS.

Removing that fixed my issue.