Black bar flashes at top of UITableView when pushing to view with "Hides Bottom Bar When Pushed" in IB

Question

This is a weird error that may just be an issue in Xcode for all I know. I have a tab bar controller where the first view is a UITableView with (obviously) a number of cells. When you select a cell, I've set up a segue on the MainStoryboard to go to a detail view controller. I want the tab bar to be hidden when I go to the detail view, so I went into the storyboard, chose my detail view, and clicked "Hides Bottom Bar on Push" in the editor screen that starts with "Simulated Metrics."

Everything works just fine, except that when I tap on a cell, a black bar flashes at the top of the UITableView screen, dropping the tableview cells down (as if the cells are falling down below the tab bar at the bottom), just before the screen pushes over to the detail view. The effect isn't harmful at all, but it's very disconcerting, and I'd like to smooth that out.

The only fix I've found is to uncheck the "Hides Bottom Bar when Pushed" option on the storyboard. That indeed does get rid of that black bar flash, but of course the tab bar stays on the screen when I go to the detail view, which is what I don't want.

Any ideas?

Just for completeness' sake, I went ahead and ran

[self.navigationController setToolbarHidden:YES animated: YES];

on the detail view controller's viewWillAppear method (and even tried it with the storyboard option both on and off), but there was no difference. The toolbar did indeed hide just fine, but I still got that black line at the top. So weird.

Answer 1

I know it is too late !!! I ran into same issue. It seems like the Auto resizing mask for the view was incorrect to be exact the UIViewAutoresizingFlexibleTopMargin. I checked this on in the xib file. If you are trying to do it in code make sure this flag -UIViewAutoresizingFlexibleTopMargin - is not included in the autoresizing mask.

Hope this will help some one in the future

Answer 2

I know it is a bit late, but I have same problem and I can't solve it with any of the previous answers. (I suppose this is the reason non was accepted).

The problem is that view size of the SecondViewController is same as view size of a previous ViewController, so too small to fit in a ViewController with Toolbar hidden. Thats why black background of a UITabBarController is visible at the top when transition is happening, and on a viewDidAppear view will stretch on right size.

For me it help to subclass root UITabBarController and set background color to same background color as SecondViewController has.

class RootViewController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.backgroundColor = Style.backgroundColor
    }
}

Then you can leave checkbox checked inside storyboard and it will look ok.

P.S.

If you have some views, that is position on the bottom part of the view, you need to set bottom constraints so they are smaller by 49 (because this is the height of the toolbar), and then on viewDidAppear set the right constraint.

For example:
I have view that need to be position 44 px from bottom edge. Before, I have constraint set to 44 and I have some strange behaviour of that view. It was placed to height and then jump on the right place.
I fix this with setting constraint to -5 (44-49), and then in viewDidAppear set the constraint back to 44. Now I have normal behaviour of that view.

Answer 3

Wow I just had the same issue now, very painful, and no info on the net about it.

Anyway, a simple workaround for me was to change the current view's Frame moving the y coordinates up and making the height bigger by the height of the tab bar. This fixed the problem if done straight after pushing the new view onto the navigation controller. Also, there was no need to fix the Frame afterwards (it must be updated when the view is shown again).

MonoTouch code:

UIViewController viewControllerToPush = new MyViewController();
viewControllerToPush.HidesBottomBarWhenPushed = true; // I had this in the MyViewController's constructor, doesn't make any difference
this.NavigationController.PushViewController(viewControllerToPush, true);
float offset = this.TabBarController.TabBar.Frame.Height;
this.View.Frame = new System.Drawing.RectangleF(0, -offset, this.View.Frame.Width, this.View.Frame.Height + offset);

Objective C code (untested, just a translation of the monotouch code):

UIViewController *viewControllerToPush = [MyViewController new];
viewControllerToPush.hidesBottomBarWhenPushed = YES;    viewControllerToPush.hidesBottomBarWhenPushed = YES;
float offset = self.tabBarController.tabBar.frame.size.height;  float offset = self.tabBarController.tabBar.frame.size.height;
self.view.frame = CGRectMake(0, -offset, self.view.frame.width, self.view.frame.height + offset);   self.view.frame = CGRectMake(0, -offset, self.view.frame.size.width, self.view.frame.size.height + offset);