UIDocumentInteractionController presentPreviewAnimated: returning NO and not showing preview

Question

I've tried everything I can think of and it still responds NO and Apple's doesn't have any hints.

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"finished!");

    NSString *tempString = [NSString stringWithFormat:@"file://%@%@", NSTemporaryDirectory(), [[NSProcessInfo processInfo] globallyUniqueString]];
    NSURL *tempURL = [NSURL URLWithString:tempString];
    [receivedData writeToURL:tempURL atomically:YES];

    NSLog(@"tempURL is written!");

    UIDocumentInteractionController *interactionController = [UIDocumentInteractionController interactionControllerWithURL:tempURL];
    interactionController.delegate = self;
    [interactionController retain];
    NSLog(@"--- %i", [interactionController presentPreviewAnimated:YES]);
    NSLog(@"presented preview");

    [connection release];
    [receivedData release];
}

- (UIViewController*)documentInteractionControllerViewControllerForPreview:(UIDocumentInteractionController *)controller
{
    NSLog(@"asdf");
    UIViewController *viewController = [[[UIViewController alloc] init] autorelease];
    [self.navigationController pushViewController:viewController animated:YES];
    return viewController;
}

Answer 1

1) are you confident the document you're opening is kosher? If not, then returning NO would be the thing to expect

2) I'm puzzled by your delegate method. The present method is happy to do the pushing onto the navigation controller all by itself. Do you fair any better if you use this code instead? (See the docs for rationale.)

- (UIViewController *) documentInteractionControllerViewControllerForPreview: (UIDocumentInteractionController *) controller
{
    return [self navigationController];
}