The Core iOS Developer’s Cookbook, Fifth Edition

Web Services

It is becoming difficult to build an iOS app of any significance these days without interacting with one or more web services. Nearly all data available on the Internet, both public and private, is provided via a web service.

These utilitarian network endpoints generally use HTTP with messages encoded as JSON or XML. The APIs for these services are published publically for many sites. While many require registration to use, a few are still fully accessible. Private enterprise web services are only documented and accessible to those who have the correct authorization.

Apple provides the tools required to download and process most web services with ease. The URL Loading System gets and posts your data, and provided parsers can interpret ...