I am using the DropBox Core API in my app and therefore, I must include the XCTest framework, because, when I haven't added the XCTest framework, my app can't connect to dropbox, however when I do add the framework, I get an error while building for the simulator. There is nothing wrong with my code! Here is the error: Ld /Users/Zach/Library/Developer/Xcode/DerivedData/SnapDrop!-fchnxyvnqyeefscfhmohrzxtiqeb/Build/Products/Debug-iphonesimulator/SnapDrop!.app/SnapDrop! normal i386 cd "/Users/Zach/Desktop/SnapDrop!" setenv IPHONEOS_DEPLOYMENT_TARGET 6.1 setenv PATH "/Applications/Xcode5-DP6.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode5-DP6.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin" /Applications/Xcode5-DP6.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch i386 -isysroot /Applications/Xcode5-DP6.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.0.sdk -L/Users/Zach/Library/Developer/Xcode/DerivedData/SnapDrop!-fchnxyvnqyeefscfhmohrzxtiqeb/Build/Products/Debug-iphonesimulator -F/Users/Zach/Library/Developer/Xcode/DerivedData/SnapDrop!-fchnxyvnqyeefscfhmohrzxtiqeb/Build/Products/Debug-iphonesimulator -F/Users/Zach/Downloads/dropbox-ios-sdk-1.3.5 -F/Users/Zach/Downloads/dropbox-ios-sync-sdk-1-1.1.0 -F/Applications/Xcode5-DP6.app/Contents/Developer/Library/Frameworks -F/Users/Zach/Desktop -filelist /Users/Zach/Library/Developer/Xcode/DerivedData/SnapDrop!-fchnxyvnqyeefscfhmohrzxtiqeb/Build/Intermediates/SnapDrop!.build/Debug-iphonesimulator/SnapDrop!.build/Objects-normal/i386/SnapDrop!.LinkFileList -Xlinker -objc_abi_version -Xlinker 2 -fobjc-arc -fobjc-link-runtime -Xlinker -no_implicit_dylibs -mios-simulator-version-min=6.1 -framework iAd -framework AssetsLibrary -framework QuartzCore -framework SystemConfiguration -framework Security -framework CFNetwork -framework XCTest -framework Dropbox -framework DropboxSDK -framework CoreGraphics -framework UIKit -framework Foundation -Xlinker -dependency_info -Xlinker /Users/Zach/Library/Developer/Xcode/DerivedData/SnapDrop!-fchnxyvnqyeefscfhmohrzxtiqeb/Build/Intermediates/SnapDrop!.build/Debug-iphonesimulator/SnapDrop!.build/Objects-normal/i386/SnapDrop!_dependency_info.dat -o /Users/Zach/Library/Developer/Xcode/DerivedData/SnapDrop!-fchnxyvnqyeefscfhmohrzxtiqeb/Build/Products/Debug-iphonesimulator/SnapDrop!.app/SnapDrop! ld: building for iOS Simulator, but linking against dylib built for MacOSX file '/Applications/Xcode5-DP6.app/Contents/Developer/Library/Frameworks/XCTest.framework/XCTest' for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invocation) What should I do? If my framework is corrupt, can you tell me how to reinstall it? I have tried deleting and reinstalling Xcode with no luck.