Programming iOS 6, 3rd Edition

Loading Web View Content

To load a web view with content initially, you’re going to need one of three things:

An NSURLRequest

Construct an NSURLRequest and call loadRequest:. An NSURLRequest might involve a file URL referring to a file on disk (within your app’s bundle, for instance); the web view will deduce the file’s type from its extension. But it might also involve the URL of a resource to be fetched across the Internet, in which case you can configure various additional aspects of the request (for example, you can form a POST request). This is the only form of loading that works with goBack (because in the other two forms, there is no URL to go back to).

An HTML string

Construct an NSString consisting of valid HTML and call loadHTMLString:baseURL:. The baseURL: will be used to fetch any resources referred to by a partial (relative) URL in the string. For example, you could cause partial URLs to refer to resources inside your app’s bundle.

Data and a MIME type

Obtain an NSData object and call loadData:MIMEType:textEncodingName:baseURL:. Obviously, this requires that you know the appropriate MIME type, and that you obtain the content as NSData (or convert it to NSData). Typically, this will be because the content was itself obtained by fetching it from the Internet (more about that in Chapter 37).

There is often more than one way to load a given piece of content. For instance, one of Apple’s own examples suggests that you display a PDF file in your app’s bundle by loading ...