Images not loading FIRST time a UIWebView is used

Question

My original plan was to use a split view controller to have a table view and a generic view beside it for an iPad app. Then I realized I could not use a split view controller as a child controller. So, I've been experimenting with using a table view controller instead, and I've got pretty good results so far. Essentially, I'm using the tableview's header view as a container for the various views I'll be using depending on which row is selected. The only unresolved issue is that images for a website are not displayed in the UIWebView the first time it is presented. If I tap another table row that displays a web view, it displays fine. And if I tap the original one again, it displays fine, too.

It doesn't matter which one I tap first. It's always the first one that doesn't display images. Instead of displaying the images, it displays the names of the image files.

When I tried the analogous thing with a split view controller, I didn't have this problem.

Any ideas what I should be looking for? Or is there something I need to be doing that I must not be doing?

If it matters, the page being loaded is just a thumbnail page on a remote server, created with Irfanview's HTML thumbnail page generator.

P.S. After further testing, it is really the very first presentation only that doesn't work as expected. By very first, I mean the first per app session. The UIWebview is presented as a subview of the table header. The tableview controller is presented as a popover from a button of another controller that is presented when a user taps an image. Even if I dismiss all these layers of controllers, etc., if I instantiate them again, the UIWebView displays properly.

This suggests possibly loading a dummy UIWebView before starting, but that seems kludgy.

I'm getting exactly one call to webViewDidStartLoad: and exactly one call to webViewDidFinishLoad: and no calls to webView:didFailLoadWithError:.

KLUDGE: The kludge works. Here it is:

In my table view controller, I create a boolean property URLHasBeenRequested and set it to NO in viewDidLoad. Then I ask for a reload thus:

-(void)webViewDidFinishLoad:(UIWebView *)webView
{
   if (!self.URLHasBeenRequested) {
      //On first pass, try a second request.
      [webView loadRequest:webView.request];
      self.URLHasBeenRequested = YES;//Set this flag so a duplicate request happens only the first time.
   }
}

TonyB TonyB · Accepted Answer · 2013-11-01T14:14:31

I suspect this has more to do with the way the UITableView is loading the header and trying to allocate memory during that process, than with the UIWebView itself. For whatever reason, the UIWebView's loading seems to be getting interrupted while the rendering of the UITableView is still finishing ( just a guess ).

One thing you might try would be to go ahead and setup your table header by adding the UIWebView subview, but not calling "loadRequest" right away. You could, for example, wait until the rest of the visible cells of the table have been loaded, and then load the header view last. You can detect when that occurs like this:

-(void) tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if([indexPath row] == ((NSIndexPath*)[[tableView indexPathsForVisibleRows] lastObject]).row){
        [webView loadRequest:webView.request];
    }
}

This is, admittedly, also a somewhat kludgy workaround, but at least you're not having the UIWebView load the content twice. I also haven't tested this myself, and without seeing your actual table loading code, it's hard to say if the root of the problem lies somewhere else, but let me know if this works!

Images not loading FIRST time a UIWebView is used

1 Answers