iOS: Scroll UITableView back to the top after popping ViewController

Question

My UITableView needs to scroll all the way to the top after popping back to ViewController under certain circumstances.

The code below works fine (I edited it for simplicity), but I am hoping to find a better way without using a delay timer. If I don't use a timer the UITableView doesn't scroll all the way to the top because the ViewController hasn't loaded yet (I think).

DetailController.m

- (void)popToViewController {
    // pop back to ViewController.
    [self.navigationController popViewControllerAnimated:YES];

    // Calls ViewController method
    [self.viewController method];
}

ViewController.m

- (void)method {
   dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.1 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
            [self.tableView setContentOffset:CGPointZero animated:NO];
        });
}

I tried using ViewDidAppear in ViewController and it works, but it gets called all the time if I pop the ViewController. I only need to scroll the UITableView all the way up under certain circumstances.

Edit: I also tried dispatch_async, but it doesn't work all the time.

Use a delegate method going back from detailVC to masterVC. There you can pass a parameter with the conditions and then in masterVC you can decide to scroll or not. — koen, Jun 05 '18 at 19:35
Possible duplicate of [UITableView - scroll to the top](https://stackoverflow.com/questions/724892/uitableview-scroll-to-the-top) — Will Jones, Jun 05 '18 at 19:53

score 0 · Accepted Answer · answered Jun 05 '18 at 19:44

It is possible to add a completion block for the animation. Remove your timer and try something like this:

- (void)popToViewController {
    [CATransaction begin];

    [CATransaction setCompletionBlock:^{
        [self.viewController method];
    }];

    [self.navigationController popViewControllerAnimated:YES];

    [CATransaction commit];
}

iOS: Scroll UITableView back to the top after popping ViewController

1 Answers1