Dynamically increase/decrease height of custom UINavigationBar

Question

I followed this blog post that explains how you can implement a custom UINavigationBar that has an increased height, if for example you wanted to put additional ui elements in the nav bar underneath the rest of the bar content that will persist between navigation on the stack. This code works really well in the case where you always want it to be that increased height.

In my app, I need to start the navigation bar at its default height, then increase it later, adding more content, after the user performs a given action. Very similar to the song info and controls in the iTunes Store:

So I put some checks in place to not reposition anything if a BOOL property is NO. When I set it to YES, I call [self setNeedsDisplay] which will call layoutSubviews to position everything appropriately based on that boolean value. sizeThatFits is also called and I return the proper height.

The problem is, I can't call [self setTransform:CGAffineTransformMakeTranslation(0, -(NavigationBarHeightIncrease))]; in initialize. Instead I call that at the same time I change the boolean value to YES. Because of this, all of my elements are moved up that amount. But if I don't call setTransform, the elements in the nav bar are in the proper position, but the bar itself is positioned too far down, so that the custom view I've added to the bar is shown overtop the view controller's view - it bleeds out, and the extra space I added is black not the navigation bar's background color.

If I call setTransform in initialize, when the height is the default height, the elements are moved up when they shouldn't be.

So, how can I properly dynamically change the height and positioning of a UINavigationBar subclass?

Answer 1

As suggested in the comments, to achieve the behavior where a custom navigation bar (not subclassing the native control) persists across pushes and pops of controllers in a navigation controller, you'll need to have a single controller with the custom navigation bar and then a single embedded view that resolves to a UINavigationController with its view controllers underneath. Then, it will also be necessary to set the navigation controller's delegate to the root controller so that the title and other properties can be updated as the sub-controllers are pushed and popped. I've provided a screenshot below of what the storyboard version of this might look like: