How to save locally saved xml file into .plist file

I need to write and update XML file based on nodes.

For that I found that I need to convert local XML file into plist file.

Then I can able to update, read and write into plist file as we need.

But I didn't found any sample code regarding this.

Can anyone please post some code regarding how can I save local xml file into plist file?

How can I read, write and update that locally saved plist file?