Apple Mach-O Linker Error - Objective C

I got this error while compiling my existing project on XCode. I try to use the quickstart from Google Drive (Step 3) https://developers.google.com/drive/ios/quickstart and after completed all of the 8 steps, I got 4 errors of Apple Mach-O linker error. Then I undid all of the steps, but even worse. ``` Undefined symbols for architecture i386: "_initGenericErrorDefaultFunc", referenced from: ___23+[DDXMLNode initialize]_block_invoke in DDXMLNode.o "_xmlAddChild", referenced from: -[DDXMLElement addAttribute:] in DDXMLElement.o -[DDXMLElement addChild:] in DDXMLElement.o -[DDXMLElement insertChild:atIndex:] in DDXMLElement.o _xmpp_xmlStartElement in XMPPParser.o _xmpp_xmlCharacters in XMPPParser.o "_xmlAddPrevSibling", referenced from: -[DDXMLElement insertChild:atIndex:] in DDXMLElement.o "_xmlBufferCreate", referenced from: -[DDXMLNode XMLStringWithOptions:] in DDXMLNode.o "_xmlBufferFree", referenced from: -[DDXMLNode XMLStringWithOptions:] in DDXMLNode.o "_xmlCopyDoc", referenced from: -[DDXMLNode copyWithZone:] in DDXMLNode.o "_xmlCopyDtd", referenced from: -[DDXMLNode copyWithZone:] in DDXMLNode.o "_xmlCopyNamespace", referenced from: -[DDXMLNode copyWithZone:] in DDXMLNode.o "_xmlCopyNode", referenced from: _xmpp_onDidReadRoot in XMPPParser.o -[DDXMLNode copyWithZone:] in DDXMLNode.o "_xmlCopyProp", referenced from: -[DDXMLNode copyWithZone:] in DDXMLNode.o "_xmlCreatePushParserCtxt", referenced from: -[XMPPParser initWithDelegate:delegateQueue:parserQueue:] in XMPPParser.o "_xmlCtxtGetLastError", referenced from: ___24-[XMPPParser parseData:]_block_invoke in XMPPParser.o "_xmlDocGetRootElement", referenced from: -[DDXMLDocument rootElement] in DDXMLDocument.o _xmpp_postEndElement in XMPPParser.o _xmpp_xmlSearchNs in XMPPParser.o _xmpp_postStartElement in XMPPParser.o "_xmlDocSetRootElement", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlEncodeSpecialChars", referenced from: -[DDXMLNode setStringValue:] in DDXMLNode.o -[DDXMLNamespaceNode setStringValue:] in DDXMLNode.o -[DDXMLAttributeNode setStringValue:] in DDXMLNode.o "_xmlFree", referenced from: _xmpp_xmlStartElement in XMPPParser.o -[DDXMLNode setStringValue:] in DDXMLNode.o -[DDXMLNode stringValue] in DDXMLNode.o -[DDXMLNamespaceNode setName:] in DDXMLNode.o -[DDXMLNamespaceNode setStringValue:] in DDXMLNode.o -[DDXMLAttributeNode setStringValue:] in DDXMLNode.o _xmpp_xmlStartElement in XMPPParser.o -[DDXMLNode setStringValue:] in DDXMLNode.o -[DDXMLNode stringValue] in DDXMLNode.o -[DDXMLNamespaceNode setName:] in DDXMLNode.o -[DDXMLNamespaceNode setStringValue:] in DDXMLNode.o -[DDXMLAttributeNode setStringValue:] in DDXMLNode.o "_xmlFreeDoc", referenced from: -[XMPPParser dealloc] in XMPPParser.o -[DDXMLNode dealloc] in DDXMLNode.o -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlFreeDtd", referenced from: -[DDXMLNode dealloc] in DDXMLNode.o "_xmlFreeNode", referenced from: -[DDXMLNode dealloc] in DDXMLNode.o +[DDXMLNode removeChild:] in DDXMLNode.o +[DDXMLNode removeAllChildrenFromNode:] in DDXMLNode.o "_xmlFreeNs", referenced from: -[DDXMLNode dealloc] in DDXMLNode.o +[DDXMLNode removeNamespace:fromNode:] in DDXMLNode.o +[DDXMLNode removeAllNamespacesFromNode:] in DDXMLNode.o -[DDXMLAttributeNode dealloc] in DDXMLNode.o -[DDXMLAttributeNode setURI:] in DDXMLNode.o "_xmlFreeParserCtxt", referenced from: -[XMPPParser dealloc] in XMPPParser.o "_xmlFreeProp", referenced from: -[DDXMLNode dealloc] in DDXMLNode.o +[DDXMLNode removeAttribute:] in DDXMLNode.o +[DDXMLNode removeAllAttributesFromNode:] in DDXMLNode.o "_xmlIndentTreeOutput", referenced from: -[DDXMLNode XMLStringWithOptions:] in DDXMLNode.o "_xmlKeepBlanksDefault", referenced from: -[DDXMLDocument initWithData:options:error:] in DDXMLDocument.o ___23+[DDXMLNode initialize]_block_invoke in DDXMLNode.o "_xmlNewComment", referenced from: +[DDXMLNode commentWithStringValue:] in DDXMLNode.o "_xmlNewDoc", referenced from: -[XMPPParser initWithDelegate:delegateQueue:parserQueue:] in XMPPParser.o -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlNewDocNode", referenced from: _xmpp_xmlStartElement in XMPPParser.o "_xmlNewNode", referenced from: -[DDXMLElement initWithName:] in DDXMLElement.o -[DDXMLElement initWithName:URI:] in DDXMLElement.o -[DDXMLElement initWithName:stringValue:] in DDXMLElement.o "_xmlNewNs", referenced from: _xmpp_xmlStartElement in XMPPParser.o +[DDXMLNode namespaceWithName:stringValue:] in DDXMLNode.o -[DDXMLNode setURI:] in DDXMLNode.o +[DDXMLNode recursiveMigrateNamespace:to:node:] in DDXMLNode.o +[DDXMLNode recursiveFixDefaultNamespacesInNode:withNewRoot:] in DDXMLNode.o -[DDXMLAttributeNode detach] in DDXMLNode.o -[DDXMLAttributeNode setURI:] in DDXMLNode.o ... "_xmlNewNsProp", referenced from: _xmpp_xmlStartElement in XMPPParser.o "_xmlNewPI", referenced from: +[DDXMLNode processingInstructionWithName:stringValue:] in DDXMLNode.o "_xmlNewProp", referenced from: _xmpp_xmlStartElement in XMPPParser.o +[DDXMLNode attributeWithName:stringValue:] in DDXMLNode.o +[DDXMLNode attributeWithName:URI:stringValue:] in DDXMLNode.o "_xmlNewText", referenced from: +[DDXMLNode textWithStringValue:] in DDXMLNode.o -[DDXMLAttributeNode setStringValue:] in DDXMLNode.o "_xmlNewTextLen", referenced from: _xmpp_xmlCharacters in XMPPParser.o "_xmlNodeDump", referenced from: -[DDXMLNode XMLStringWithOptions:] in DDXMLNode.o "_xmlNodeGetContent", referenced from: -[DDXMLNode stringValue] in DDXMLNode.o "_xmlNodeSetContent", referenced from: -[DDXMLNode setStringValue:] in DDXMLNode.o -[DDXMLAttributeNode setStringValue:] in DDXMLNode.o "_xmlNodeSetName", referenced from: -[DDXMLNode setName:] in DDXMLNode.o "_xmlParseChunk", referenced from: ___24-[XMPPParser parseData:]_block_invoke in XMPPParser.o "_xmlParseMemory", referenced from: -[DDXMLDocument initWithData:options:error:] in DDXMLDocument.o "_xmlSaveNoEmptyTags", referenced from: -[DDXMLNode XMLStringWithOptions:] in DDXMLNode.o "_xmlSearchNs", referenced from: -[DDXMLElement elementsForName:] in DDXMLElement.o -[DDXMLAttributeNode URI] in DDXMLNode.o "_xmlSetStructuredErrorFunc", referenced from: ___23+[DDXMLNode initialize]_block_invoke in DDXMLNode.o "_xmlStopParser", referenced from: _xmpp_xmlAbortDueToMemoryShortage in XMPPParser.o "_xmlStrEqual", referenced from: -[DDXMLElement _elementsForName:localName:prefix:uri:] in DDXMLElement.o -[DDXMLElement _hasAttributeWithName:] in DDXMLElement.o -[DDXMLElement _removeAttributeForName:] in DDXMLElement.o -[DDXMLElement attributeForName:] in DDXMLElement.o -[DDXMLElement _removeNamespaceForPrefix:] in DDXMLElement.o -[DDXMLElement namespaceForPrefix:] in DDXMLElement.o -[DDXMLElement _recursiveResolveNamespaceForPrefix:atNode:] in DDXMLElement.o ... "_xmlStrQEqual", referenced from: -[DDXMLElement attributeForName:] in DDXMLElement.o "_xmlStrdup", referenced from: -[DDXMLNamespaceNode setName:] in DDXMLNode.o "_xmlStringLenDecodeEntities", referenced from: _xmpp_xmlStartElement in XMPPParser.o "_xmlUnlinkNode", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlXPathEvalExpression", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlXPathFreeContext", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlXPathFreeObject", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlXPathNewContext", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o "_xmlXPathRegisterNs", referenced from: -[DDXMLNode nodesForXPath:error:] in DDXMLNode.o ld: symbol(s) not found for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invo cation) ``` Please help me, I've been stuck for more than 4 days :(