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Lập trình ứng dụng cho iPhone part 20

The web: web views and internet protocols Chúng tôi bắt đầu cuốn sách này với một cái nhìn tại trang web. Chương 3 thông qua 8 cung cấp một thảo luận rộng rãi xây dựng các ứng dụng web của iPhone bằng cách sử dụng HTML, CSS, JavaScript, và lập trình ngôn ngữ năng động của sự lựa chọn của bạn. Như chúng tôi đã nói lúc đó, phát triển web là một trong hai cách chính mà bạn có thể lập trình cho iPhone, các khác đang được các SDK mà chúng tôi đã dành chương cuối cùng trên mười | The web web views and internet protocols This chapter covers Using web views Parsing XML Accessing other protocols We started this book with a look at the web. Chapters 3 through 8 offered an extensive discussion of building iPhone web apps using HTML CSS JavaScript and the dynamic programming language of your choice. As we said at the time web development is one of two major ways that you can program for the iPhone the other being the SDK that we ve spent the last ten chapters on. We ve generally suggested web apps as the proper platform for creating internet-related programs. This chapter will present some solutions for when that s not the case. Even if you re depending heavily on the web there are numerous reasons that you might want to program using the SDK. You might want to make use of its more extensive graphic capabilities. You could be designing something of sufficient complexity that you want to use a well-organized object-oriented environment. You might want to monetize your app without having to depend on ads. For whatever 396 Low-level networking 397 reason you ve decided to design an SDK web app not an HTML-based web app and now you need to know how to do so. In this chapter we re going to cover the major ways to access the internet from the SDK. You can do so in a variety ofways and we ll outline their hierarchy in our first section. 20.1 The hierarchy of the internet internet programming involves a hierarchy of protocols. At the lowest level you have the sockets that you use to connect from one computer to another. Above them are a variety of more sophisticated technologies such as FTP Bonjour and HTML. HTML is a critical protocol represented on the iPhone by both low-level access and the high-level UlWebView. Recently an increasing number of protocols have been built on top of HTML forming what we call the social network. This hierarchy of internet protocols is shown in figure 20.1 along with iPhone OS classes of note. Low-level Networking BSD .