'libxml/tree.h' file not found

　　Lexical or Preprocessor lssue 'libxml/tree.h' file not found

　　解决方法：

　　1.在Build Phases——>Link Binary With Libraries中，导入libxml2.dylib;

　　2.在Build Settings——>Search Paths——>Header Search Paths中，添加/usr/include/libxml2。