I am confused of validating some of the fields such as email_id ,web address in my project.These fields should accept the standard format (for eg: firstname.lastname@example.org, www.ddd.com). How can i do this? I m a biginner in mac programming . I use xcode 3.1 , I B 3.1 and objective-C for programming . Please give me some tips with examples to overcome this problem . thank you.