如何将NSURLconnection http响应数据与iphone中的字符串值进行比较？

i am new in iphone programming......i want to do an activation module which will send a http request with a PIN numbr and then read the response...if the response is "OK" it opens up with a main menu...........the problem is that i am recieving the response as "OK" but i am unable to compare it with a NSString @"OK"............so how to compare the http response with a string...........please give ur suggestions...thanks.i am new in iphone programming......i want to d