gistfile1.m

- (void)onCatalog
{
	RSSCatalogController *c = [[RSSCatalogController alloc] initWithNibName:@"RSSCatalogController" bundle:nil];
	c.title = @"Catalog";
#ifdef USE_BLOCKS
	UIActivityIndicatorView *scrollerView = [[[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite] autorelease];
	[scrollerView startAnimating];
	UIBarButtonItem *scrollerItem = [[[UIBarButtonItem alloc] initWithCustomView:scrollerView] autorelease];
	UIBarButtonItem *oldItem = [self.navigationItem.rightBarButtonItem retain];
	[self.navigationItem setRightBarButtonItem:scrollerItem animated:YES];
	
	NSOperationQueue *q = [[NSOperationQueue alloc] init];
	[q pl_addOperationWithBlock:^{
		// форкнули выполнение в поток
		[c updateCategories]; // <--- медленная операция
		[[NSThread mainThread] pl_performBlock: ^{
			// вернулись в основной поток
			[self.navigationItem setRightBarButtonItem:[oldItem autorelease] animated:YES];
			[self.navigationController pushViewController:c animated:YES];
			[c release];
			[q autorelease];
		}];
	}];
#else
	[c updateCategories];
	[self.navigationController pushViewController:c animated:YES];
	[c release];
#endif
}