How to transition smoothly from translucent to opaque UINavigationBar iOS?

The black color you're seeing is the background color of the UINavigationController's view. One way to minimize seeing it is to manipulate the background color of that view to the color of the outgoing / incoming view controller's view. This works well if you're working with solid colors. Another approach is to extend your views behind the opaque navigation bar using UIViewController.extendedLayoutIncludesOpaqueBars = YES;

always use Translucent, plus add an uiview with a color below it and animate it's alpha?

Set the UIWindow background color to your Navigation bar's tintColor.

I finally found a decent solution!

There doesn't appear to be a proper way to smoothly transition from an opaque to transparent UINavigationBar BUT you can transition smoothly from a view controller with a visible status bar to one that has a hidden status bar.

This opens up a possible workaround which is to add the following in the viewWillAppear of VC2 from above:

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

Once you have that, manually add a UINavigationBar to your xib and configure it to be transparent (and add all necessary UIBarButtonItem and views).

If everything is hooked up properly transitioning from VC1 to VC2 will hide the UINavigationBar at the same speed as the view transition and VC2 will show up with it's embedded UINavigationBar

Note: To make this work properly you'll have to make sure that in the viewWillAppear of View Controllers that can be accessed from VC2 you reset the UINavigationBar to be visible (if necessary) via:

[self.navigationController setNavigationBarHidden:NO animated:YES];

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TL;DR - manually add a UINavigationBar to your transparent nav bar view controller and in its viewWillAppear hide the default one via setNavigationBarHidden:animated: