QLPreviewController works on iOS 6; not on iOS 7

Question

I've reviewed other posts regarding QLPreviewController not working under certain conditions. This one has me stymied:

RHBlobCollectionand RHBlobView are model/view objects that respectively hold the collection of, and the individual displayable files, cached ahead of time.

RHBlobView.m:

    - (IBAction) handleBlobTap:(UITapGestureRecognizer *)sender
    {
        QLPreviewController *previewController = [[QLPreviewController alloc] init];

        // view tag is index in array of blobs
        [previewController setCurrentPreviewItemIndex:self.tag];

        // blobContainer is type RHBlobCollection
        [previewController setDataSource:self.blobContainer];

        UINavigationController *navController = (UINavigationController *)[[[[UIApplication sharedApplication] delegate] window] rootViewController];
        [navController pushViewController:previewController animated:YES];

    }

RHBlobCollection.m:

    - (NSInteger) numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller
    {
        return [self.blobs count];
    }

    - (id <QLPreviewItem>) previewController:(QLPreviewController *)controller
                          previewItemAtIndex:(NSInteger)index
    {
        RHBlobView *blob = self.blobs[(NSUInteger) index];

        NSURL *fileURL = [RHCacheManager cachedFileURLForFilename:blob.filename withKey:blob.blobID];

        // URL proper?
        BOOL __unused proof1 = [fileURL isFileURL];

        // QLPreviewController can stomach it?
        BOOL __unused proof2 = [QLPreviewController canPreviewItem:fileURL];

        // Cached file actually exists?
        NSString *proof3path = [[fileURL resourceSpecifier] stringByReplacingPercentEscapesUsingEncoding:NSISOLatin1StringEncoding];
        BOOL __unused proof3 = [[NSFileManager defaultManager] fileExistsAtPath:proof3path];

        // Unless we're dealing with thumbnails, we're done. Return the URL of the resource.
        if ( ! [blob hasThumbnails] )
        {
            return fileURL;
        }

        // Process thumbnails into .pdf file for display...

proof1, proof2 and proof3 all return YES. Pulled out into a separate proof-of-concept project, QLPreviewController does as it's supposed to. In my full app project, though, it works under iOS 6 but hangs on "Loading..." with a spinner under iOS 7.

My gut tells me that it should have something to do with a malformed file URL or path, but my little tests show everything is copasetic. Has anyone else had a problem with this?

Answer 1

For sake of completeness, I found the issue. I was actually using a subclass of NSURL, a simple affair that just added a separate string for the human-readable document title (previewItemTitle). When I changed things back to NSURL, things started working. Ugly titles for some weird filenames, but at least they appear. Back to the drawing board for how to handle that problem...

Answer 2

I would agree Under 6 previewItemAtIndex index is > 0 while with 7 index is Always -1 no matter the count Can you confirm ?