Web Services and UIWebView - iOS Programming: The Big Nerd Ranch Guide - page 702

For the More Curious: The Request Body
When NSURLConnection talks to a web server, it uses the HTTP protocol. This pro-
tocol says that any data you send or receive must follow the HTTP specification. The actual
data transferred to the server in this chapter is shown in Figure 25.10 .
Figure 25.10 HTTP Request Format
NSURLRequest has a number of methods that allow you to specify a piece of the request
and then properly format it for you.
Any service request has three parts: a request-line, the HTTP headers, and the HTTP body,
which is optional. The request-line (which Apple calls a status line) is the first line of the
request and tells the server what the client is trying to do. In this request, the client is trying
to GET the resource at smartfeed.php?limit=1_DAY&etc . (It also specifies the
HTTP specification version that the data is in.)
The command GET is an HTTP method. While there are a number of supported HTTP
methods, you typically only see GET and POST . The default of NSURLRequest , GET , in-