淡出NavigationBar标题

Question

I have a scrollView with paging enabled. When i start to drag to the next page i want to text in my navigationBar smoothly fade out. I do it with delegate method:

-(void)scrollViewDidScroll:(UIScrollView *)scrollView

I calculate the percent of dragging with:

CGFloat percentDragging = 1 - fmodf(scrollView.contentOffset.x,self.view.frame.size.width)/self.view.frame.size.width;

And this return right values.

So: I try to set:

self.navigationController.navigationBar.titleView.alpha = percentDragging

but it didn't work.

I solved the problem by:

((UIView*)[[self.navigationController.navigationBar subviews] objectAtIndex:1]).alpha = percentDragging;

But this is ugly, crude, dangerous solution. There is a better way?

Answer 1

Setting the titleView 's alpha didn't work because that doesn't give you access to the default navigation-bar title label—it only has a value when you've set one. I think what you'll have to do here is set a custom titleView yourself, containing a UILabel with font/shadow/etc. set to match the standard style, and fade that label in and out with your transition.