Overlapping headings in the navigation bar

Question

I have a ViewController with a button that animates, pushes the second viewController onto the navigation stack.

On this second controller, I have a button with an action that animated pops itself from the navigation stack.

If I repeatedly and quickly click them one after another, the headings in the navigation bar will overlap with each other.

Here is a screenshot of the overlapping names:

How can I get rid of this problem?

Edit:

I have the same problem, it is randomly generated. I have a UIViewController with a UITableView , by clicking on the UITableViewCell , it will go into the UITableViewController.

Sometimes the title of the UITableViewController overlays the title of the UIViewController when I click the back button.

NOTE. There are no custom headers or custom navigation controls; all controls are standard controls.

The navigation header was set using the code below:

 self.title = @"Mail (28)"; 

I use

Xcode Version 8.0 (8A218a)

IPhone 7 Simulator - iOS10 (14A345)