iPhone: extracting text from and Disk-Cache of retrieved web page

Question

My iPhone app has an Info page, which contains a UIWebView, which I have pointed at my website's info page:

NSString *urlAddress = @"http://www.toneme.org/Software";
NSURL *url = [NSURL URLWithString: urlAddress];
NSURLRequest *requestObj = [NSURLRequest requestWithURL: url];

[self.webView loadRequest:requestObj];

However, every time the user loads the app they will get a blank screen for ages until it fetches the data. This is not good.

It would be far better to display the last page loaded, whilst trying to fetch a new version in the background. But I can't see how to do this cleanly. could somebody get me started?

A second question: for the iPhone it is not practical to display this webpage in a UIWebView, as the webpage contains three panes; the whole thing just won't fit. I really want to extract the text from the page. Is there any clean way of doing this? Can I specify that I only want to download the main body?

I'm guessing the whole page gets returned as a single string, so maybe if I fit a couple of homemade tags around my text, this would simplify extracting the text manually...

Answer 1

Provide an HTTP API which provides the text in some format you can parse (i.e., JSON, XML) that will allow you to download that data, store it locally (more on this in a second), and construct a view out of that downloaded data to display nice and pretty. :)

With respect to storing the data, look at writing a class which saves the data to your application's Documents directory, and handles looking at the server http header info, to see if the file needs to be re-downloaded, or if it's already up to date (this can be done using etags ideally, but the last-modified-date if etags are not supported in your infrastructure).

Answer 2

As doing this yourself is surely possible, but quite some work to get right, you might want to check AsiHTTPRequest and especially ASIWebPageRequest

HTH

Answer 3

You should be able to save the UIWebView contents and the URL data to a file for reuse in the delegate webViewDidFinishLoad method using

NSString *myHtml = [webView stringByEvaluatingJavaScriptFromString:@"document.documentElement.outerHTML"];