How to write XML for any Website

Hi frnds
I am very new to XML,Websites HTTP and all.
My problem is I want to use XML file to send and receive data in client/server model(developing in objective C).
I know nothing about how to design XML for any website in general and then use in project of client server.
My main target is to login to a webserver or any server then do further data exchange.
Can somebody show a wayout.
I have wasted more than a week but unable to find any solution.

You probably haven't found a solution because you know nothing about using XML.

Step 1: Learn. Google is your friend.

XML has been designed to standardize communication, which is especially handy for communicating between several parties, as the structure of the document can be formally written down in a document and can be validated, so there is no discussion afterwards about the syntax of the document.

Although that is a noble idea, XML is relatively complex and not as light weight as, for example, json.

As long as you are writing your own client that communicates to your own server, the protocol used between those 2 can be anything, and do not need to be XML.

I am doing Objective C programming and I want send and receive requests(Login/data fetching) over the client/server. Now the problem is Should I do it using XML or any other Method. Also I know nothing how to write XML for any particular website. I am hassling for many days.Can anybody help?

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