Iphone – Using a UIWebView with loadHTMLString/loadData breaks the back and forward buttons, workaround

cachingiphoneuiwebview

There's a known problem with embedded UIWebViews that if you load data into them using loadHTMLString or loadData, the canGoBack/canGoForward properties and goBack/goForward methods don't work. These only work when using loadRequest.

Since Safari's normal app cache doesn't work in embedded UIWebViews, creating a native app that effectively caches otherwise live content becomes impossible/unusable. That is, I can cache the contents of the HTML, Javascript, images, etc. and load them via loadHTMLString or loadData, but then the back and forward buttons don't work.

I could also use loadRequest and specify a file URL, but that breaks when it comes to communicating with the live site — even if I specify a tag (because of cookie domain issues).

I have a work around that involves basically re-implementing the app cache using local store (and not having the native app do any caching itself), which is OK, but not really ideal. Are there any other work arounds/something I missed?

Best Answer

I am using the UIWebView's canGoBack to check to see if I'm at the first page of the history. If I am then I just call the little method I used to load the first page (displayLocalResource sets up the HTMLString and loads it into the webView). Here is a snippet:

//Implementing a back button
- (void)backOne:(id)sender{
    if ([webView canGoBack]) {
        // There's a valid webpage to go back to, so go there
        [webView goBack];
    } else {
        // You've reached the end of the line, so reload your own data
            [self displayLocalResource];
        }
    }
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