UIScrollView not showing scroll indicator

Question

I have a UIScrollView which I create and size dynamically using...

scrollView.contentSize = CGSizeMake(scrollView.frame.size.width , length);

Answer 1

I fix this by adding this code after add new subview:

self.showsVerticalScrollIndicator = NO;
self.showsVerticalScrollIndicator = YES;

Answer 2

For me, the horizontal indicator had mysteriously disappeared in my app on iOS 7. Later found out that for some strange reason, I had to enable both Shows Horizontal Indicator and Shows Vertical Indicator to make the horizontal one show up. If I set it to not show the vertical indicator, it would also not show horizontal indicator.