I know how to read text file from the ftp server.I have used this logic for rtf file.But it gives wrong out put.Is it possible to read rtf file from the server?If possible then please help me.
You need software that understands the rtf file format. Microsoft Word does. Most plain text editors will not be able to show you the contents of a file in rtf format.
Google for rtf format
Added: didn't notice that you're on an iPhone platform. Google for "rtf iphone" and you'll see several choices including http://prmac.com/release-id-4180.htm