iOS Programming: The Big Nerd Ranch Guide, 6th Edition

For the More Curious: HTTP

When URLSessionTask interacts with a web server, it does so according to the rules outlined in the HTTP specification. The specification is very clear about the exact format of the request/response exchange between the client and the server. An example of a simple HTTP request is shown in Figure 20.7.

Figure 20.7  HTTP request format

A simple HTTP request is shown. The request is seen as a rectangular section with two narrow, rectangular portions at the top and bottom. The request contains the content such as host, connection, cookie, etcetera. These are collectively labeled headers. The narrow ...