Display of results is delayed by 5s in UISearchDisplayController

My UISearchDisplayController performs asynchronous searches via NSOperationQueue.

However the results table does not visually update until approximately 5s after the NSOperation calls [searchDisplayController.searchResultsTableView reloadData].

- (BOOL) searchDisplayController:(UISearchDisplayController*)controller shouldReloadTableForSearchString:(NSString*)searchString
{
    [searchQueue cancelAllOperations];
    NSInvocationOperation *op = [[[CustomSearchOperation alloc] initWithController:controller searchTerm:searchString] autorelease];
    [searchQueue addOperation:op];

    return NO;
}

My CustomerSearchOperation updates the tableView like so:

- (void) main
{
    // perform searc开发者_C百科h

    [searchDisplayController setContents:results];
    [searchDisplayController.searchResultsTableView reloadData];
}

The problem is that UI updates must occur on the main thread, and reloadData is being called from a background thread via the NSOperationQueue.

You can use the NSObject method performSelectorOnMainThread:withObject:waitUntilDone: to ensure such updates occur on the main thread.

- (void) main
{
    // perform search

    [sdc setContents:results];
    [sdc.searchResultsTableView performSelectorOnMainThread:@selector(reloadData)
                                withObject:nil
                                waitUntilDone:NO];
}