UIWebView getting stuck after webViewDidStartLoad - ios

Question

Our iOS app has a Web View that is rendering pages from file: URLs. When the user touches an <A> element to switch pages, about 20% of the time, it gets stuck as follows:
User taps <A> link
We get WebView.shouldStartLoadWithRequest callback
We get WebView.webViewDidStartLoad callback
nothing happens after this
The screen still shows the original page with the link on it. We can break the logjam in two ways:
Rotate the device
Tap the screen
At that point, the page will immediately finish loading.
We used the recipe from here:
Javascript console.log() in an iOS UIWebView
to allow us some insight into the page load. We put the javascript-side stuff right in the first script file we load on the page, and it doesn't print its message until after we do the rotate-or-tap workaround.
So it appears that it is getting stuck somewhere between starting to load the page, and starting to evaluate the stuff on the page.
We have tried a number of work-around, none of which helped:
Setting location.href instead of using the tag
Setting location.href from javascript timeout
In the didStartLoad callback, created a thread that called setNeedDisplay on the webView over and over
Any idea what we might be doing wrong?

Answer 1

You could use gdb within XCode to debug the problem. I think canidates for messages that could have break points are:
- (void)webViewDidStartLoad:(UIWebView *)webView
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
I'd also add a break in whatever UIViewController is showing your UIWebView for:
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
Then you could step through and hopefully catch what's wrong with your UIWebView subclass.
If you don't want to add breakpoints you could just run your app in the XCode debugger and hit the "pause execution" button above the console window when your app becomes unresponsive while loading.
It's hard to know what's going on without any code to go off of but I bet Xcode can help you find the issue quickly.
Good luck!

Answer 2

Found the solution for this weird behavior, at least in my case.
In my App i've created a subclass of UIWebView. I know that Apples documentation notes that you should not subclass UIWebView. But it's "necessary" in my App.
The problem was, that i've overwritten scrollViewDidEndDragging:willDecelerate: without calling super.
- (void) scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
// my code
}
becomes to
- (void) scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
[super scrollViewDidEndDragging:scrollView willDecelerate:decelerate];
// my code
}
Now it always loads the web site when tapping on a html link.