hide navigation bar

[dfing]

I use tableView in each contentView and I put it all in navigationController.

when I scroll the tableView, according to scrollView.contentOffset.y, I hide/show my navigation bar.
use [self.navigationController setNavigationBarHidden:YES animated:YES]; in the tableViewController
In most of the time, It work fine. like this

BUT sometime, it will work break, like this

the navigation bar has hidden, but the tabs view not change it's contentOffset.y
It seem to happen when I scroll the tableView first.

My question is that It's the lib bug or I write wrong code?

[dfing]

I found that first scroll the tableview, the layoutSubviews in ViewPagerController not work, even I call it.

ViewPagerController *vpc = (ViewPagerController *)self.parentViewController;
[vpc.view setNeedsLayout];