Question

My issue is that the back button will not restore its visibility if my web request does not finish before or soon after ViewWillAppear has fired.

I have a navigation based iPhone 4.0 application used a simple Root and Detail view setup.
I am working with data that is returned from a webservice so when I push my detail view in its ViewDidLoad function I call my web service method in a separate thread and the Iphone lifecycle does its thing on the main thread. I must disable/hide the back button until the web request has finished (or failed) so I call self.navigationItem.hidesBackButton = YES; in ViewDidLoad and self.navigationItem.hidesBackButton = NO; in the delegate function which fires once my web request has finished or failed.

I already tried the following:

[self.navigationItem performSelectorOnMainThread:@selector(setHidesBackButton:) withObject:NO waitUntilDone:NO];
[self.navigationItem setHidesBackButton:NO];
[self.view setNeedsDisplay];
[self.navigationController.view setNeedsDisplay];

UINavigationItem *nav = self.navigationItem;
nav.hidesBackButton = NO;

Root View Controller Push Code:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
 ArticleViewController *articleViewController = [[ArticleViewController alloc] initWithNibName:@"ArticleViewController" bundle:nil];
 NewsArticle *newsArticle = [newsItems objectAtIndex:indexPath.row];
 articleViewController.articleID = newsArticle.newsID;
 [self.navigationController pushViewController:articleViewController animated:YES];

 [newsArticle release];
 [articleViewController release];
}

Details View Controller Code:

- (void)viewDidLoad {
 [super viewDidLoad];

 self.navigationItem.hidesBackButton = YES;
 id scrollView = [[[self webContent] subviews] objectAtIndex:0];
 if([scrollView respondsToSelector:@selector(setBackgroundColor:)] )
 {
  [scrollView performSelector:@selector(setBackgroundColor:) 
       withObject:[UIColor blackColor]];
 }

 [self getNewsArticle];
}

//Fires when the web request has finished
- (void) finish:(NewsArticle *)newsArticleFromSvc {
 self.navigationItem.hidesBackButton = NO;
 self.newsArticle = newsArticleFromSvc;
 [self bindNewsArtice];
}

Any help is GREATLY appreciated I can hardly @#$&^ believe that hiding a button in a UI could cause me this much wasted time.

Answer 1

I wasn’t able to solve this problem. Instead I tweaked my App Logic to make hiding he back button not necessary.