I ' m guessing you already find it out, but just for the record:the uikit.framework are available only on IOS platform. The path /system/library/frameworks/ contains the frameworks that your MAC OS X have installed (not your Xcode).
The iOS frameworks that was used in IOS projects, at least when using Xcode, is the following:
/applications/xcode6-beta4.app/contents/developer/platforms/iphoneos.platform/developer/sdks/iphoneos8.0.sdk/ System/library/frameworks
The Xcode6-beta4.app part of the path is the app name of your Xcode in your Applications folder, so can be some What different if you have another version installed. Also, theiphoneos8.0.sdk can be different if you ' re using other SDK version (IOS 7.0, for example).
Edit:if the uikit.framework is there and then you probably changed some configuration in your Xcode. The easier-to-fix it is probably by deleting it and reinstalling.
Emulator SDK Path