找不到架构i386的符号？

Question

我正在尝试使用多个标记来实现地图。但我对这个错误感到困惑。

架构i386的未定义符号：

  "_xmlFreeDoc", referenced from:

      +[MTDXMLElement nodesForXPathQuery:onXML:namespacePrefix:namespaceURI:] in MTDirectionsKit(MTDXMLElement.o)

  "_xmlReadMemory", referenced from:

      +[MTDXMLElement nodesForXPathQuery:onXML:namespacePrefix:namespaceURI:] in MTDirectionsKit(MTDXMLElement.o)
  "_xmlXPathEvalExpression", referenced from:

      +[MTDXMLElement mtd_nodesForXPathQuery:namespacePrefix:namespaceURI:libXMLDoc:] in MTDirectionsKit(MTDXMLElement.o)

  "_xmlXPathFreeContext", referenced from:

      +[MTDXMLElement mtd_nodesForXPathQuery:namespacePrefix:namespaceURI:libXMLDoc:] in MTDirectionsKit(MTDXMLElement.o)
  "_xmlXPathFreeObject", referenced from:

      +[MTDXMLElement mtd_nodesForXPathQuery:namespacePrefix:namespaceURI:libXMLDoc:] in MTDirectionsKit(MTDXMLElement.o)
  "_xmlXPathNewContext", referenced from:

      +[MTDXMLElement mtd_nodesForXPathQuery:namespacePrefix:namespaceURI:libXMLDoc:] in MTDirectionsKit(MTDXMLElement.o)
  "_xmlXPathRegisterNs", referenced from:

      +[MTDXMLElement mtd_nodesForXPathQuery:namespacePrefix:namespaceURI:libXMLDoc:] in MTDirectionsKit(MTDXMLElement.o)
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

有人可以通过“未找到i386架构的符号”来解释它的含义。