I want to compare two XML documents to find and show where is the difference
like diff utility in XCode.
我想比较两个XML文档，以找到和显示XCode中的diff实用程序的不同之处。
I can retrieve and parse xml code using NSXMLParser in basic level,
and can tell 'they are not exactly same'
我可以在基本级别上使用NSXMLParser检索和解析xml代码，并且可以告诉“它们不完全相同”
but I don't know how to tell 'where and which'.
但我不知道如何分辨“在哪里，在哪里”。
Is there any open-source based library for this?
有基于开源的图书馆吗?
Thanks in advance.
提前谢谢。