Question

I have an app with long data list in the tableView, and I would like to double tap the navigationBar to scroll the UITableView on top of the list (where the search is).

How can I implement that?

Thanks for your help.

Answer 1

The standard gesture for scrolling a tableView to the top is a single tap on the status bar. It’s enabled by default see UIScrollView Reference

If you really want the navigation bar and you’re targeting 3.2 and up I would recommend to attach an UITapGestureRecognizer to the navigationBar.

- (void)viewDidLoad {
    UITapGestureRecognizer* tapRecon = [[UITapGestureRecognizer alloc]
              initWithTarget:self action:@selector(navigationBarDoubleTap:)];
    tapRecon.numberOfTapsRequired = 2;
    [navController.navigationBar addGestureRecognizer:tapRecon];
    [tapRecon release];
}

- (void)navigationBarDoubleTap:(UIGestureRecognizer*)recognizer {
    [tableView setContentOffset:CGPointMake(0,0) animated:YES];
}

If you’re targeting 3.0 or below it could become a little tricky and is not recommend.