Question

I have a view controller that is sub class of UIViewController which has table view into it and each rows in table view is linked to distinct xml url. I made a parser class that is sub class of NSOperation and implemented methods to parse the XML file on selection of each row as,

   -(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
[tableView deselectRowAtIndexPath:indexPath animated:YES];
[self performSelectorOnMainThread:@selector(pushView) withObject:nil waitUntilDone:NO];
[self performSelectorInBackground:@selector(parseOperation:) withObject:indexPath];
}

-(void)pushView{
detailView = [[viewDetailsController alloc] initWithNibName:@"viewDetailsController" bundle:nil];
[self.navigationController pushViewController:detailView animated:YES]; 
}

 -(void)parseOperation:(NSIndexPath *)indexPath{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
self.queue = [[NSOperationQueue alloc] init];
parserClass *parser = [[parserClass alloc] initWithParseUrl:[[self.arrayOfUrls objectAtIndex:indexPath.row]delegate:self];
[queue addOperation:parser];
[parser release];
[pool release];
}

Parser works great but in its custom delegate method I have called to push view controller on the top of the navigation controller stack, the view controller initializes correctly but the new view controller is not pushed into the screen.
I dont have any idea about why this is not working.

Answer 1

All UI calls must be made from the main thread, which may include allocating/initializing UI classes. It sounds like you are breaking that rule in your custom delegate method.