Beginning iOS 5 Application Development

16

Using Web Services

WHAT YOU WILL LEARN IN THIS CHAPTER

• Understanding the various ways to consume Web services in your iPhone applications
• How to communicate with a Web service using SOAP
• How to communicate with a Web service using HTTP GET
• How to communicate with a Web service using HTTP POST
• How to communicate with a JSON Web service
• Parsing the result of a Web service call using the NSXMLParser class
• How to integrate Twitter into your application

Communicating with the outside world is one of the ways to make your iOS applications interesting and useful. This is especially true today when so many Web services provide such useful functionality. However, consuming Web services in an iOS is not for the fainthearted. Unlike other development tools (such as Microsoft Visual Studio), Xcode does not have built-in tools that make consuming Web services easy. Everything must be done by hand, and you need to know how to form the relevant XML messages to send to the Web services and then parse the returning XML result.

This chapter explains how to communicate with XML Web services from within your iOS application. Working through the examples in this chapter will give you a solid foundation for consuming other Web services that you will need in your own projects. Besides consuming XML Web services, you will also learn how to consume a much more efficient type of Web service — JSON Web services.

In addition, this chapter covers one of the new APIs in iOS 5 — integrating with Twitter. ...