Automatic scroll to top doesn't work in UITableView

Question

usually when tapping the top of the screen the tableview scrolls all the way to the top. For some reason this doesn't work in one of my view controllers.

The hirarchy is as follows:

UIView
-> WebView
-> TableView
----->SearchBar
SearchDisplayController.

I think I have everything hooked up correctly (datasource, delegate, ...). I have a similar view controller where everything works. The only difference seems to be WebView, which is missing in the view controller where the tap-and-scroll-to-top works...

Any ideas?

Best regards, Sascha

Answer 1

You have probably added some view to your view hierarchy that is a UIScrollView or contains scroll views (e.g. UIWebView or UITextView). When you tap the status bar, iOS searches for the topmost scrollview with scrollsToTop set to YES and scrolls to its top.

Add this to your class:

- (void) disableScrollsToTopPropertyOnAllSubviewsOf:(UIView *)view {
    for (UIView *subview in view.subviews) {
        if ([subview isKindOfClass:[UIScrollView class]]) {
            ((UIScrollView *)subview).scrollsToTop = NO;
        }
        [self disableScrollsToTopPropertyOnAllSubviewsOf:subview];
    }
}

…and call

[self disableScrollsToTopPropertyOnAllSubviewsOf:myAddedSubview];

to solve the problem and let your table view scroll to top again.

Answer 2

You need to disable scrollsToTop on all but one of the scrollable views. Since UITableView is a descendant of UIScrollView, it's easy to do. However, if you want to disable it on the webview, it's a little trickier. This seems to work:

[webView.subviews objectAtIndex:0].scrollsToTop = NO;

But that is a little iffy since it's poking around in undocumented parts of the webview. It may stop working if Apple decides to rearrange the subviews.