找不到Xcode CoreFoundation / CFUserNotification.h'文件

我不知道为什么我这样做，当我在xcode4.6build立一个iPad项目。 iOS sdk 6.1，模拟器6.1。

/Applications/Xcode4.6.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.1.sdk/System/Library/Frameworks/CoreFoundation.framework/Headers/CoreFoundation.h:92:10: 'CoreFoundation/CFUserNotification.h' file not found In file included from /Applications/Xcode4.6.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.1.sdk/System/Library/Frameworks/Foundation.framework/Headers/Foundation.h:5:10