Ios 在项目中添加AFNetworking framework时出错

在项目中添加AFNetworking framework时，我遇到以下错误：-

Undefined symbols for architecture i386:
  "_UTTypeCopyPreferredTagWithClass", referenced from:
      _AFContentTypeForPathExtension in AFURLRequestSerialization.o
  "_UTTypeCreatePreferredIdentifierForTag", referenced from:
      _AFContentTypeForPathExtension in AFURLRequestSerialization.o
  "_kUTTagClassFilenameExtension", referenced from:
      _AFContentTypeForPathExtension in AFURLRequestSerialization.o
  "_kUTTagClassMIMEType", referenced from:
      _AFContentTypeForPathExtension in AFURLRequestSerialization.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

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我正在使用xcode 4.5和sdk iOS 6.0，在您的项目中添加以下框架：

MobileCoreServices.framework
SystemConfiguration.framework

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你添加了所有必需的框架了吗？就是这样，我忘了MobileCoReserves，以为它与iOS 7有关！谢谢你，伙计，帮我省点时间。